same genus which occur in the Uitenhage beds and in order to broaden the foundation for future work. From statements made in the Reports mentioned above, it seems that in our present state of knowledge no satisfactory subdivision of the Uitenhage beds is possible, and that the members of the series are so variably developed that no consistent nomenclature is to be hoped for until detailed mapping can be carried out. Of the subdivisions hitherto employed, the uppermost member of the series, the Sunday's River or Marine Beds, has yielded the majority of the Mollusca which are discussed in this paper. The underlying "Wood Bed" series has also furnished a few species of marine molluscs in addition to Unio and remains of fossil plants. The socalled Enon Beds represent the lowest division of the formation in this district. Messrs. Rogers and Schwarz, while indicating the local significance of the adopted subdivisions, draw attention to the limited value of this nomenclature, and mention facts which clearly show the contemporaneous variation of facies in the series. Thus, to the north of Uitenhage, the Marine Beds appear to be synchronous with part of the local conglomerate of "Enon" character, and it is pointed out that at Plettenberg's Bay also, the Sunday's River Beds are partly replaced by conglomerate resembling that of the Enon Beds, but here yielding Trigonia conocardiformis, one of the most characteristic fossils of the Marine Beds.* The question of the age to be assigned to the Uitenhage Series, as is well known, has called forth strikingly different opinions from various authors. It was suggested by Stow in 1871 † that the want of unanimity among the earlier writers might have been due to careless collecting and the mingling of specimens obtained from different horizons. This author therefore made his own collections with due regard to the localities and the individual bands in which he found the fossils to occur, and he attempted a correlation of the fossiliferous beds exposed in sections at various places on the Sunday's and Zwartkop's Rivers. It appears highly probable, however, from the palæontological evidence alone, that no very considerable extent of time is represented by the whole of the beds which yield marine fossils, and there is nothing to show that the different opinions. respecting the age of the series have been arrived at in consequence of any radical change in the character of the fauna itself in its distribution through the strata. That any such marked change can be * Schwarz (1), pp. 53, 61; Rogers and Schwarz (1), p. 5; Rogers (1), pp. 282– 296. See also Rogers (2), pp. 13, 15. + Stow (1). traced is not evident from the table of sections given by Stow.* There are, no doubt, minor differences, and local distribution according to facies in the successive fossiliferous bands, which may be more clearly revealed when the district comes to be mapped in detail; but there is certainly nothing so far-reaching in this respect as to have formed grounds for the differences of view expressed, for instance, by Tate, who ascribed an Oolitic age to the fauna, and Neumayr, who referred these beds to the Neocomian.† The divergent conclusions arrived at by the earlier authors appear rather to have resulted from the different interpretations put upon the same peculiar association of forms when viewed in comparison with the limited standards of European type. The principal difficulty seems to have lain in the fact that none of the fossils could be correctly identified with those of formations studied in other regions, and the facies of the fauna, taken as a whole, did not seem to show such agreement with that of any known assemblage as to give it the decided stamp which might serve to put the question of age beyond dispute. This matter has been so frequently dealt with, and its bearings are so well known, that it may seem superfluous to dwell upon it here at any length; but it may be useful to recapitulate briefly the successive opinions expressed, and in some cases the grounds upon which they were based, before proceeding to the more thorough comparison of the fauna with its extra-European equivalents which recent knowledge has rendered possible. I take this opportunity of expressing my indebtedness to Mr. A. W. Rogers for the helpful manner in which he has furnished me with information relating to the collections; to Dr. A. Smith Woodward, Mr. G. C. Crick, and Mr. R. B. Newton for facilitating reference to literature and specimens in the British Museum (Natural History); and to Mr. W. Rupert Jones for his ready assistance during my repeated examinations of the extensive collection of Uitenhage fossils in the museum of the Geological Society of London. My best thanks are also due to Prof. J. W. Gregory for examining a specimen of Thamnastrea submitted to him, and to Mr. C. D. Sherborn for assistance in a few matters relating to bibliography; to Mr. G. W. Lamplugh, Mr. H. A. Allen, and Mr. H. Woods, I am indebted for several useful suggestions. * Stow (1), fig. 3. See further remarks on this subject at the end of Section II. of the present paper. In this connection see Neumayr's remarks on Stow's work; Holub and Neumayr (1), p. 270, footnote 6 II. THE AGE OF THE FAUNA. (a) Summary of Previous Work.-In 1837, Hausmann recorded the occurrence of some shells obtained by Hertzog from strata in the Sunday's River district, to which he ascribed a Lower Cretaceous age. These included a Hamites, which was compared with H. intermedius J. Sow. and H. funatus Brongn., and a Trigonia which was thought to resemble T. dædalea Park.* Goldfuss afterwards described and figured two of Hausmann's shells under the names Lyrodon herzogi and Cytherea herzogi, and also considered them to be of Greensand age.t The examination of a small collection of lamellibranchs obtained by F. Krauss in 1839 from strata exposed on the Zwartkop's River, led that author to the conclusion that they indicated a Lower Greensand horizon, and in another paper Krauss furnished excellent descriptions and figures of these shells, maintaining a similar view concerning their age.§ In 1851 a collection of fossil plants and molluscs, obtained by R. Rubidge on the Sunday's River, was exhibited before the British Association at Ipswich by Colonel Portlock, who remarked that the shells were apparently of Jurassic age, while Dr. Harvey's examination of the plant remains was thought to corroborate this view.|| In his well-known paper published in 1856, A. G. Bain¶ referred the Uitenhage fossils with doubt to the Lias, basing this opinion upon the prevalence of a supposed Liassic form, "Gryphaa incurva." The shell mistaken for this, however, was Exogyra imbricata, previously described by Krauss, which, as we shall see, bears only a superficial resemblance to the Gryphaa mentioned, and is in reality closely comparable with certain Lower Cretaceous forms of Exogyra. Appended to Bain's paper were D. Sharpe's descriptions of the Secondary fossils collected by Atherstone and Bain from localities on the Sunday's and Zwartkop's Rivers. The forms described, principally Mullusca, led Sharpe to the conclusion that they most nearly resembled European species of the Middle and Lower Oolites; he compared his Ammonites atherstoni with A. macrocephalus and A. herveyi, while believing Ammonites baini to be related to A. humphresianus and other Lower Oolitic forms. * Hausmann (1), p. 1457. † Goldfuss (1), Band II., p. 202, pl. 137, fig. 5 (1837); p. 239, pl. 149, fig. 10 (1840). Krauss (1), pp. 129, 130. || Portlock (1). § Krauss (2). In 1867, a paper by Ralph Tate, in which many new forms were described and figured, added largely to our knowledge of the Uitenhage fossils, and this author was led to some remarkable conclusions from his study of the fauna. He believed the assemblage to indicate a Jurassic age, and stated that he thought it to represent the fauna of the Oolitic rocks of Europe, and to approximate to that of the Great Oolite. It seems clear that in instituting this comparison, he made use of some molluscan types little adapted to serve the purposes of a critical correlation, and he was at the same time misled by several quite erroneous identifications. He also misunderstood the affinities of the cephalopods and the significance of certain Trigonia which alone might have been expected to form obstacles to his conclusions. It is here scarcely necessary to do more than refer to the curious generalisation arrived at by Tate concerning the relation of these supposed Jurassic deposits to the Jurassic strata of Europe, namely, that the "Oolites" of South Africa are the representatives of the whole of the Jurassic rocks of Europe with the exception of the Upper Oolites, and illustrate an intermingling of palæontological types which are analogous to, or identical with, those distributed in successive zones in Europe. In his monograph on the Cretaceous lamellibranchs of Southern India, Stoliczkał made some reference to Uitenhage forms. He evidently believed Tate's Crassatella complicata to belong to the genus Ptychomya, and he ascribed Astarte herzogi Krauss to Speyer's genus Grotriania. He further expressed the opinion that Krauss's Astarte bronni might belong to the Cretaceous genus Remondia Gabb, and thought that in addition to these and Trigonia ventricosa, several other Uitenhage shells show a Cretaceous rather than a Jurassic aspect; attention was drawn to the great similarity between Trigonia ventricosa (Krauss) and the Cretaceous T. tuberculifera Stol., from Southern India. While we shall see that Stoliczka rightly recognised some of the Uitenhage forms to exhibit Cretaceous affinities, he was in error in ascribing Astarte herzogi to the genus Grotriania, and, as afterwards pointed out by Neumayr, wrongly supposed Astarte bronni to belong to the genus Remondia. A. bronni is so distinctly characterised that Neumayr proposed for it the new generic name Seebachia-a fact which appears to have been overlooked by Stanton, who in 1897 still tentatively included it in the genus Remondia.‡ One of Tate's Uitenhage species, the so-called Crassatella com* Tate (1). ↑ Stoliczka (2), pp. 286, 294, 315 (1871). Stanton (1). plicata, was later also recognised by Dames to be a representative of the genus Ptychomya,* and this seemed to point to a later age for the strata from which it was obtained than that assigned by Tate. Dames was further led to the belief in the Neocomian age of the Uitenhage beds by a fragment of an ammonite (sent by Krauss to L. von Buch) which he thought to be identical with Ammonites astierianus d'Orb. In the concluding chapter of his monograph on the British Fossil Trigonia, Lycett† referred briefly to the Trigonia of the Uitenhage Formation, and expressed his opinion that some of the most characteristic of these point decisively to a Cretaceous age; he also showed that the alleged occurrence of T. goldfussi, which Tate had used as evidence for a Jurassic age, rested on an erroneous determination. The whole question of the age of this fauna was afterwards well handled by Neumayr, who subjected Tate's work to some criticism. Neumayr set on one side many molluscan types as of little significance in a comparative study, and concluded that a costate Trigonia (T. tatei Neum.) alone exhibited a marked Jurassic character. On the other hand, he considered a number of forms to represent essentially Cretaceous types. Such were Holcostephanus atherstoni (Sharpe); Holcostephanus baini (Sharpe); Crioceras spinosissimum (Hausm.) Neumayr; Trigonia ventricosa (Krauss); Trigonia conocardiiformis (Krauss); Ptychomya complicata (Tate)§; and Exogyra imbricata Krauss. He suggested that Tate's Ammonites subanceps, which was thought by Tate to resemble the Jurassic A. anceps Rein., might really represent the young of Crioceras spinosissimum. It was admitted by Neumayr that Belemnites africanus Tate, which Tate placed in the group Canaliculati and considered to afford strong evidence for an Oolitic age, bears a strong resemblance to the Jurassic forms B. canaliculatus Schloth. and B. magnificus d'Orb.; but at the same time he drew attention to the existence of a belemnite in the Lower Cretaceous of North Germany which seemed to share some of the characteristics of B. africanus. In a later paper, written after an examination of Tate's original specimen in the collection of the Geological Society, Neumayr || definitely separated B. africanus from the Canaliculati, and included it in his group of the Absoluti, which, as he remarked, extend in their occurrence up to the Aptian; hence the conclusive nature of the * Dames (1). Holub and Neumayr (1). || Neumayr (4). Lycett (3), p. 230 (1879). 66 § Misquoted implicata " by Neumayr. |