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Show 1878.] MR. E. J. MIERS ON THE PENiEID^E. 305 with some hesitation to this species, in the Museum collection. The rostrum is of the form described by Milne-Edwards, but reaches but little beyond the peduncle of the antennules, and scarcely at all beyond the antennal scale. The fifth pair of legs is considerably longer than the preceding, and very slender; the dactylus small, of the usual form. This species cannot be the male sex of P. dobsoni, described above, as it differs in the form of the postabdominal segment, which is rounded at its antero-lateral angle, in the existence of spines on the lateral margins of the last postabdominal segment, &c. The median dorsal carina is prolonged to the posterior margin of the cephalothorax ; and there is a raised lateral line on each side, extending from a point immediately above the antennal spine halfway to the posterior margin. If the genus Xiphopeneus of Smith (Trans. Conn. Ac. ii. p. 26, 1871) be sustained, it will probably be necessary to refer this species to it, as it agrees in the form of the rostrum, and in the length of the legs of the fifth pair, although the dactylus is quite short. PENEEUS KROYERI. Peneus kroyeri, Heller, Wien. Akad. Wissensch. Sitzungsb. xiv. (Abth. i.), p. 425, pl. ii. fig. 51 (1862). Xiphopeneus harttii, Smith, Trans. Conn. Ac. ii. p. 28, pl. i. fig. 1 (1871). I have little hesitation in referring the Xiphopeneus harttii of Smith, from Caravelhas, Bahia, to the previously described P. kroyeri of Heller, from Rio Janeiro. A comparison of the figures and descriptions will, I think, suffice to establish their identity: and there is a specimen from the West Indies in the British-Museum collection which appears to belong to the same species. The genus Xiphopeneus was characterized by its author mainly by the long and slender antennules (which have a small lamelliform appendage which is not foliaceous and expanded over the eye as in Peneeus), the form of the cephalothoracic sulci, and the great length of the fourth and fifth thoracic legs (which have the terminal joints slender and flagelliform or, rather, styliform). The mouth-organs, antennae, &c. are not different from those of Peneeus. It will be seen that these characters are not of greater value than those which distinguish the Peneei of Milne-Edwards's first and second sections (which have never been considered of generic importance). Moreover the length of the posterior legs is certainly a character that varies in the different species ; and in one (P. styliferus) already referred to, which agrees in most of its characters with Xiphopeneus, the dactylus of the fifth pair of legs is quite short. Nor do we know at present how far these peculiarities are dependent upon the sex of the animals (the specimens of P. kroyeri and P. styliferus in the Museum collection are both males). If the genus Xiphopeneus be retained as distinct, it will be necessary to constitute more than one other new generic division for species hitherto included in Peneeus ; and as the materials at present existing PROC. ZOOL. Soc-1878, No. XX. 20 |