to the Lower Cretaceous; but in a more recently published tabular correlation of the geological formations of the Transvaal and Cape Colony, Molengraaff has ascribed them with a note of interrogation to the Middle Jurassic. In 1896 R. B. Newton published a useful summary of previous work on the Cretaceous conchology of South Africa, and furnished a complete list of the known Mollusca from the Uitenhage beds, which he classed as Neocomian. In their textbooks de Lapparent and Kayser § have followed Holub and Neumayr in assigning a Neocomian age. Passarge, in his work on the Kalahari, has tabulated the Uitenhage Series with the Upper Jurassic and Lower Cretaceous. Lemoine believes it to be of Lower Cretaceous age.T

(b) Additional Evidence for Age.-We see from the foregoing that a comparison of the Uitenhage Mollusca with European forms seems to point definitely to a Lower Cretaceous age, for it will be conceded that the evidence of the Cephalopoda must be allowed to carry the greatest weight in influencing a decision. The representatives of Holcostephanus (sensu stricto), Hamites and Crioceras already recorded, supply in themselves sufficiently striking evidence, and notable additions to these are other forms of Holcostephanus, as well as representatives of Acanthodiscus and Bochianites included in the collections submitted for examination and described in these pages. Two other species of Holcostephanus (sensu stricto), hitherto undescribed, are represented in the collection of the Geological Society of London. One of these is apparently allied to H. atherstoni (Sharpe), but has greater lateral compression as well as other distinctive characters. It closely resembles H. psilostomus Neum. and Uhlig, of the European Neocomian, and is the "compressed variety" of H. atherstoni mentioned by Pavlow,** who aptly suggested close relationship to a shell from the Neocomian of Spain, figured by Nicklès as Holcostephanus hispanicus. The significance of such an assemblage of Cephalopoda in the Uitenhage beds cannot be mistaken, quite apart from the bivalve forms to be mentioned below and a representative of the Crustacean genus Meyeria. In Europe the known species of Holcostephanus (sensu stricto) are almost wholly, if not entirely, confined to strata of Upper Valanginian and Lower Hauterivian age.

In his paper on the Uitenhage fauna R. Tate †† gave a tabular list

* Molengraaff (2), p. 119.

de Lapparent (1), p. 1267.

|| Passarge (1), p. 82; see also p. 597.

† Newton (2).

§ Kayser (1), p. 444. Lemoine (1), pp. 383, 389.

** Pavlow and Lamplugh (1), pp. 492, 496, (134 and 138 of authors' copy).

tt Tate (1), p. 166.

of some of the more important fossils, together with their supposed extra-African allies and analogues, which, with one exception, were thought to be Jurassic. An examination of this list shows, however, that a different construction must now be put upon the comparisons, as may be demonstrated by the mention of a few examples. In addition to Holcostephanus atherstoni and H. baini, which were erroneously thought to be allied to well-known Oolitic forms, there is Tate's Ammonites subanceps, a single specimen, regarding which that author wrote: "It is doubtful whether this be not a mere variety of A. anceps Reinecke, of the Middle Oolites." As already mentioned, Neumayr thought that it might represent a stage in the individual growth of Crioceras spinosissimum, which he supposed to have had the whorls in contact at such an immature period. This may be a correct view, but it seems equally probable that we are dealing with an immature example of some species of Hoplites (sensu lato). Tate's specimen, of which his published figures convey a very imperfect and even misleading impression, shows great similarity to certain forms which have been ascribed by Sayn to Hoplites arnoldi (Pict. and Camp.), and by Toucas to H. botella Kilian. These were thought by Pavlow to have been wrongly identified, and are united by him under the name Hoplites heteroptychus, which has more recently been included by Uhlig in his narrower generic group Solgeria. A somewhat similar form has been described and figured by Bogoslowsky under the name Hoplites aff. arnoldi Pict., and this is said to occur with Belemnites lateralis Phill. above the "Rjasan-Horizont" in Russia (Mostja River). Hoplites subanceps is more closely and less coarsely ornamented than this, but there are points of agreement in the type of sculpture. Further observations on "Ammonites" subanceps are given in the remarks which follow the description of a specimen ascribed to Acanthodiscus sp., in the following pages.

*

Ostrea jonesiana Tate was compared by Tate with O. costata Sow. from the Oolites; but it is in reality a true Exogyra quite comparable with shells of the type of E. subplicata Roem.,t from the Hilsconglomerat of North Germany.

Pecten projectus was compared with P. lens Sow., but such a comparison must have little value when we remember that species of Pecten with similar broad characteristics recur at various horizons and are not confined to the Jurassic rocks. Pecten projectus, in

* Bogoslowsky (1), pp. 112, 138; Taf. vi., fig. 7.

† F. A. Roemer (1), Nachtrag, p. 25, pl. xviii., fig. 17; F. A. Roemer (2), p. 47 (1840).

fact, compares more satisfactorily with some of the Cretaceous forms.

The comparison of Pecten rubidgeanus with P. subspinosus Schloth. cannot be pronounced at all fortunate, while we shall find that Lima obliquissima shows a closer agreement of characters with Cretaceous and later forms than with the European Jurassic shells cited by Tate.

Placunopsis subjurensis Tate, which was compared with P. jurensis Roem., may perhaps be an Anomia, and in some respects closely resembles A. pseudoradiata d'Orb., * from the Aptian. Placunopsis imbricata Tate is compared in the table with P. substriata Lyc., from the Oolites. P. semistriata (Bean) was probably the English shell with which it was intended to institute comparison, since this name alone is mentioned in Tate's description on page 154 of his paper. P. imbricata, however, is without radial ornamentation, but is characterised by well-spaced concentric ridges which recall the similar ornamentation of Anomia neocomiensis d'Orb., † though occurring in less emphasised form. The illustration of P. imbricata gives a very poor idea of the shell, but an examination of the specimen dispels the notion of a close comparison with known Jurassic forms.

Trigonia cassiope Tate is not to be united with any known Jurassic costate Trigonia, and was accordingly renamed T. tatei by Neumayr. It is well distinguished by the elongated escutcheon, the very delicate marginal carina, and the fine character of the ornamentation on the area and escutcheon. Trigonia goldfussi Tate is an immature shell, and in all probability illustrates the youthful stage of one of the large and robustly ornamented Pseudo-quadrata which form such a striking feature in the Uitenhage fauna. It certainly does not represent either Trigonia goldfussi Agassiz or T. painei Lyc. (=T. goldfussi Morr. and Lyc.), with which it was identified. Tate himself, on page 159 of his paper, said: "Hereafter, however, it may be found to be the young of a distinct species." It is therefore the more regrettable that the error of quoting this European Jurassic shell from the Uitenhage beds should have continued to be perpetrated. Stow repeatedly used the name "T. goldfussi" in his paper, but I have been unable to ascertain to which of the Trigonie he referred.

No importance can be attached to the comparison of such types as

*

d'Orbigny (4), p. 84; Woods (3), vol. i., p. 27, pl. v., figs. 1–3 (1899).

t d'Orbigny (3), p. 754, pl. 489, figs. 1-3 (1848).

Stow (1), pp. 497-514.

Pinna atherstoni Sharpe and P. sharpei Tate with Jurassic forms, for it is evident that these representatives of the genus lack any strong distinctive characters which alone would render them of value in an estimate of geological age.

Mytilus baini Sharpe was compared with M. sowerbianus d'Orb., from the Oolites of Europe. It is a Modiola which certainly has characters of form and ornamentation closely similar to those which distinguished M. sowerbiana (d'Orb.) and M. perplicata (Etallon); but this type of Modiola is by no means confined to Jurassic rocks, having also a widely distributed representative in the Cretaceous M. flagellifera (Forbes), to mention a well-known example.

Pholadomya dominicalis Sharpe was thought to resemble Liassic and Oxfordian forms, but it may equally well be brought into comparison with Lower Cretaceous representatives; for example, the European Aptian shell ascribed, rightly or wrongly, to P. pedernalis Roem.*

Astarte pinchiniana Tate was brought into comparison with A. pumila Goldf. and A. excentrica Morr. and Lyc., from the Great Oolite of Europe. The African shell differs in important respects from these, and, as will be pointed out below, it probably belongs to the sub-generic group Eriphyla and is certainly most closely comparable with Cretaceous forms.

Berenicea antipodum Tate was believed by Tate to be related to B. striata Haime, from the Lower Lias of France, but has been regarded by Prof. J. W. Gregory † as a close ally of the Cretaceous B. gracilis (Milne Edwards).

Two Uitenhage Serpula were identified by Tate with S. filaria Goldf. and S. plicatilis Münst., from the Inferior Oolite of Europe. The specimens ascribed to S. plicatilis represent an adherent form sharply carinated on the back, with a weaker carinal angle on either side and a circular aperture, but the true S. plicatilis Goldf. has only a single central, longitudinal keel. S. quinquangularis Goldf. ‡ (Upper Jurassic) stands much closer in its characters, and a Serpula scarcely distinguishable from this occurs in the Lower Cretaceous of Europe, and may be found named S. quinquangularis in some collections. S. filaria Goldf. is a solitary, wholly adherent form, commencing with a coiled stage. So far as can be seen from the imperfect African specimen named S. filaria by Tate, this is a clustering form consisting of crowded, narrow cylindrical tubes, and * Pictet and Renevier (1), p. 60, pl. vi., fig. 7, 1855; Moesch (1), p. 93, pl. xxxiii., fig. 2. † Gregory (1), p. 112. Goldfuss (1), Band i., p. 230, pl. 68, fig. 8 (1831).

it is not distinguishable from the English Lower Cretaceous Serpulæ that have been variously referred to Serpula filiformis J. de C. Sow, and S. plexus J. de C. Sow. We thus see that in the case of the two Trigonia and the two Serpula which Tate identified with European Jurassic types, the determinations were so far erroneous that they are now bereft of the significance which was attached to them as evidence for the age of the fauna.

We may further examine the evidence for age afforded by some of the more conspicuous bivalves, and firstly I may briefly refer to the representatives of the genus Trigonia, which in themselves lend. such a characteristic aspect to the fauna. Although the testimony of these is perhaps not quite so conclusive as Lycett supposed, still, the balance of evidence furnished by members of this genus may be safely relied upon to give a fair indication of age, even when considered apart from associated forms, and the material we are dealing with in the present instance is fortunately of an exceptionally favourable character. In the first place there is Trigonia ventricosa, T. kraussi, and T. rogersi, all possessing the characters of the section Scabræ a division which, so far as we know, is elsewhere only represented in rocks of Cretaceous age. These might be considered to be balanced by the occurrence of T. tatei, a typical member of the section Costatæ, but although this division of the Trigonia has its maximum development in the Oolitic rocks, it is also represented in strata of Lower Cretaceous and even later age.

Trigonia peninsularis Coquand,* from the Aptian of Spain, certainly shows characters of degeneration not shared by T. tatei, but the Oomia strata of Cutch have yielded two normal representatives of the Costatæ, which, together with some degenerate derivatives of this section, are accompanied by Trigonia which exhibit a decidedly Cretaceous aspect. Another unmodified costate form, T. angustecostata Behr. † occurs in the Argentine Republic in strata which are regarded by Behrendsen as Upper Cretaceous, while a typical member of this section has been described by E. Ascher from the Grodischter beds (Hauterivian) of Silesia.

Trigonia herzogi (Goldf.), another very characteristic Uitenhage form, was believed by Lycett to belong to the Quadratæ, which, so far as known, are exclusively Cretaceous. Steinmann, § however, pointed out that Trigonia herzogi differs in several important par

Coquand (1), p. 129, pl. xxiii., fig. 3.

Behrendsen (1), p. 6, pl. 3, fig. 7.

Ascher (1), p. 159 [25], p. xiii. [ii.], fig. 10. § Steinmann (2).