GEN. DIOGENES, Dana.

1852. Diogenes, Dana, U.S. Expl. Exp., Crust., vol. xiii., pt. 1, pp. 435, 438.

1905. Diogenes, Alcock, Indian Decapod Crust., pt. 2, pp. 25, 59,

164.

Dana gave the following definition: "Ophthalmic ring bearing a rostrum. Fourth pair of feet subcheliform. Left hand the larger; fingers acuminate, calcareous at tips." He distinguished this genus and Eupagurus (which he called Bernhardus) from Paguristes by the character that they were without appendages behind the bases of the fifth leg, whereas such appendages are present in Paguristes.

DIOGENES COSTATUS, Henderson.

1893. Diogenes costatus, Henderson, Tr. Linn. Soc. London, Zool., Ser. 2, vol. v., pt. 10, p. 418, pl. 39, figs. 7, 8.

1905. Diogenes costatus, Alcock, Indian Decapod Crust., pt. 2, pp. 61, 70, pl. 6, figs. 7, 7a.

The present species belongs to the group in which "the rostrum is a slender simple (non-serrated) spicule" (Alcock). It appears to be very nearly allied to D. pugilator (Roux), known in the south of England as well as the Mediterranean and elsewhere, and to the oriental D. avarus, Heller. But the last species has a much more narrowly elongate left cheliped.

In the specimen here attributed to D. costatus the carapace has the antero-lateral margins serrulate, the rostrum shorter than the subtriangular spinulose ophthalmic scales, the antennal acicle a simple spine, strongly spinose along the inner edge, but differing from the figures in Henderson and Alcock by having a denticle on its outer edge. In describing the left cheliped Alcock says "merus a little shorter than the carpus," the reverse of which is the case in his figure and in our specimen. Both he and Henderson lay stress. on the fact that the outer surface of the palm "is traversed by a ridge which, beginning at the lower proximal angle, runs up parallel with the carpal articulation (where it is granular), and then curves round and is continued obliquely almost to the finger-cleft" (Alcock). They do not refer to what is shown in their figures, the fact that the fixed finger has on its inner margin a marked prominence fitting a corresponding cavity in the inner margin of the movable finger. The little right cheliped shows a considerable gap in the closure of the setose hand and finger.

Henderson says "the ambulatory legs are almost smooth, with the anterior margins pubescent and very faintly toothed." In our specimen the anterior margin of the carpus in the first pair of walking-legs makes an exception to this statement by being very distinctly denticulate. Alcock says of both pairs of walking-legs, that "the anterior edge of the carpus and propodite is spinulose and setose, the spinules of the carpus being the most distinct." In these limbs and the two following pairs there appear to be on the under side of the basal joints little pads of a rasp-like character, like those on the hands of the fourth and fifth legs and on the uropods. Length of carapace about 9 mm.

Locality. Great Fish Point Lighthouse, N. W., 23 miles; depth, 30 fathoms; bottom, mud. The shell occupied is covered by a branching coral.

MACRURA GENUINA.

TRIBE ERYONIDEA.

FAMILY ERYONIDE.

GEN. POLYCHELES, Heller.

1902. Polycheles, Stebbing, Marine Investigations, Crustacea, pt. 2, p. 35.

1905. Polycheles, Bouvier, Bull. Mus. Océanogr. Monaco, No. 28, p. 3.

POLYCHELES BEAUMONTII (?) (Alcock).

1894. Pentacheles Beaumontii, Alcock, Ann. Nat. Hist., Ser. 6, vol. xiii., p. 236.

1894. Pentacheles Beaumontii, Alcock, Illustrations Zool. Investigator Crustacea, pl. 8, fig. 3.

1901. Pentacheles Beaumontii, Alcock, Catal. Indian Deep-Sea Macrura, p. 175.

Faxon, in 1895, is inclined to regard this species as, at most, but a geographical race of the Polycheles granulatus, which he himself. described in 1893. The South African specimens differ in some. particulars from both accounts, but until more material is available I am unwilling to take the responsibility of instituting a new species.

The whole dorsal surface of the carapace is tomentose, the pubescence though short sufficing to conceal most of the dentation. The two rostral teeth are very small. The frontal margin has a tooth on the inner and two teeth on the outer side of the orbital notches, and there is a tooth or spine at the frontal end of the impacted eye-stalk. The teeth of the lateral margin are in groups of 8 and 4 in front of the cervical sulcus and 18 behind it, some of the last set being very small. The teeth of the median carina are small and obscure, but those behind the sulcus seem to be rather

numerous.

In the pleon the carina of the first three segments are produced forward in very small teeth, the fourth not being produced, the fifth forming a single cusp, the sixth being, as Alcock observes, without the vestige of a carina. This at least is true of the male, but in the female the front and hind margins of the segment are a little pinched. Three ridges converge on the back of the telson towards its acute point, the centre ridge commencing with a small hump.

The first antennæ have two spines on the outer side of the large first joint.

The elongate first peræopods have in the fourth joint six unequal but conspicuous teeth distributed over the middle part of one margin. In the male specimen the third joint measures 27, the fourth 38, the fifth 33, the sixth 50 millimetres, giving a total length, including the first two joints, of more than six inches. The fingers measure 27 mm. They are strongly curved at the tips. The palm to the hinge of the movable finger is 23 mm., ending in a sharp tooth, which is not adjacent to the finger.

The fifth peræopods of the female are distinctly chelate, but those of the male should perhaps not be called chelate at all. They have a process of the sixth joint subequal to the finger in length, but the grasping edge of the finger is turned not towards this process, but away from it.

The first pleopods of the male differ little from those figured by Professor Smith for P. sculptus.

The male specimen has a total length of 140 mm., of which the carapace is 64 and the pleon 76 mm. The carapace at the cervical groove is 51 mm. broad. The second antennæ are 90 mm. long.

Locality. The male specimen was obtained from a depth of 900 fathoms, Cape Point N.E. by E. E. 43 miles; the female, which is a little smaller, from 890 fathoms, Cape Point E. N. 41 miles, in each case the bottom being green mud.

POLYCHELES NANUS (Smith).

1884. Pentacheles nanus, S. I. Smith, Ann. Rep. U.S. Fish. Comm.,

1882, p. 359.

1886. Pentacheles nanus, S. I. Smith, Ann. Rep. U.S. Fish. Comm., 1885, p. 651 (47), pl. 7, figs. 1, 1a.

1895. Polycheles nanus, Faxon, Mem. Mus. Comp. Zool. Harvard, vol. xviii., p. 121, pl. 33, figs. 1, 1a, 1b.

On the middle line of the carapace, between the rostral spines and the cervical sulcus, there are two single spines one behind the other, then a pair followed by two others in single file, whereas in Professor Smith's specimen there was only one spine behind the pair. The dorsal part of the fifth pleon segment is unfortunately missing, but the fact of its loss is an indirect testimony to its original prominence. In other respects the pleon agrees with the original description, which is as follows: "The pleon is more deeply sculptured than in P. sculptus, and the dorsal carina very much higher, the recurved carinal teeth of the third, fourth, and fifth somites are very much longer and more slender, and reach far over the somites in front. The edges of the sulcated carina on the sixth somite, instead of being low and uniform, as in P. sculptus, are very high and broken into several prominent teeth on each side, with a stouter and higher tooth at the posterior end of the sulcus." The edges of the side-plates and the median elevation on the telson with its smaller secondary prominence also agree with Professor Smith's account.

According to Faxon, the fifth peræopods are chelate in both sexes; the pleurobranchiæ four, one on each of the second to the fifth peræopods, the arthrobranchiæ eight, two to each of the first to the fourth peræopods, which also have each a podobranchia; the third maxilliped has a very minute epipod, and the first to the fourth peræopods have rudimentary epipods, represented by a plate-like expansion of the base of the stem of the podobranchia.

The single South African specimen is a female, as evidenced by the sexual openings at the base of the third peræopods. Adherent to various parts of the body were several small oval eggs, but whether actually belonging to the specimen was not quite

evident.

Length of specimen 65 mm., the carapace being 30 mm. long, and at the cervical groove 22 mm. broad, the pleon 35 mm. long.

Locality.

Cape Point N.E. by E. & E. 38 miles; depth, 750-800 fathoms; bottom, green mud.

Both Smith and Faxon suggest the possibility that P. nanus may be only a dwarf deep-water variety of P. sculptus.

TRIBE SCYLLARIDEA.

1893. Scyllaridea, Stebbing, Hist. Crust., Internat. Sci. Ser., vol. lxxiv., p. 191.

This tribe, by Boas and many other writers called Loricata, comprises the two families Scyllarida and Palinuridæ. Borradaile, in his recent classification (Ann. Nat. Hist., Ser. 7, vol. xix., p. 407, 1907), retains the name Scyllaridea, but makes it one of the two "super-families" in his tribe Palinura, the Eryonidea being the other super-family. The Macroures cuirassés of Milne-Edwards, for which de Haan gives the Latin Loricata, included the Galatheidæ and the Eryonidæ as well as the two families above mentioned.

FAMILY SCYLLARIDE.

1837. "Scyllariens" (tribe), Milne-Edwards, Hist. Nat. Crust., vol. ii., p. 279.

1841. Scyllaroidea (fam.), de Haan, Crust. Japon., decas quinta, p. 148.

1847. Scyllarida, White, List of Crust. in Brit. Mus., p. 67.

1852. Scyllarida, Dana, U.S. Expl. Exp., Crust., vol. xiii., pt. 1, p. 515.

1888. Scyllarida, Bate, Challenger Macrura, Reports, vol. xxiv., p. 57.

1891. Scyllarida, Ortmann, Zool. Jahrb., vol. vi., p. 38.

1900. Scyllarida, M. J. Rathbun, Proc. U.S., Nat. Mus., vol. xxii., p. 309.

1901. Scyllarida, M. J. Rathbun, U.S. Fish. Comm. for 1900, vol. ii., p. 97.

1906. Scyllarida, M. J. Rathbun, U.S. Fish. Comm. for 1903, pt. 3, p. 896.

The genera now assigned to this family are Scyllarus, Fabricius, Scyllarides, Gill, Ibacus, Leach, Thenus, Leach, Parribacus, Dana, and Pseudibacus, Guérin-Méneville, with which Miers considers Evibacus, S. I. Smith, to be synonymous (Pr. Zool. Soc. London,