238 Transactions. — Zoology. 



Spence Bate, in the British Museum Catalogue of the Amphipodous 

 Crustacea, has overlooked the remarkable sexual differences which charac- 

 terize the Oxycephalida?, not only in this genus, hut also in Rhabdosoma, in 

 which he describes the male of R. armatum as a separate species, R. ivhitei. 

 The distinctive characters have been clearly brought out by Dr. Claus in a 

 paper on "Die Gattungen und Arten der Platysceliden," which however is 

 not readily accessible to New Zealand students. In this paper, Dr. Claus 

 describes Oxycephalus piscator, Edw., at considerable length, and unites 

 0. tuberculatus, Sp. Bate, and 0. oceanicus, Guerin-Meneville, to it — the latter 

 being a young male. He also gives brief descriptions of six new species, 

 from all of which the following species is quite distinct, though apparently 

 nearest 0. latirostris, a Lagos species. The brevity of the descriptions 

 however, and the want of illustrations, render this resemblance somewhat 

 doubtful. 



1. Oxyoephalus edwabdsh, n. sp. Plate xii., figs. 14-21 ; pi. xiii., fig. 1. 



Male. — The head is widely dilated and produced into a long sharp snout. 

 This snout is more or less sharply ridged on the upper surface, and nearly 

 flat on the under-side, the margins being sharply bent inwards. The sides 

 of the head are nearly completely occupied with the eyes, which resemble 

 those of Phronima. The sides of the head are not in close contact below, 

 but form a long groove in which the posterior antennae lie folded. The 

 anterior antennas are placed in front of the head just under the base of the 

 beak ; they depend nearly vertically, and have their concave side turned 

 outwards. The peduncle has two short basal joints, and then a long, very 

 stout, curved joint, the whole inner (convex) surface of which is thickly 

 coated with olfactory setae. The flagellum, which projects nearly at right 

 angles from the extremity of the peduncle, is very small and 3-jointed. 



The posterior antennas are placed almost behind the head, and their 

 joints lie folded closely together in the groove under the cephalon, in a 

 zigzag manner ; when extended, they are two or three times as long as the 

 head and snout. Dr. Claus calls these organs 5-jointed ; they have 4 long, 

 subequal joints, which are extremely slender, but a little dilated at their 

 ends, with a minute terminal hook-like claw, which appears only to be pre- 

 sent in mature males. The mandibles are much reduced in size, and 

 project down, behind the insertion of the antennas, as small tooth-like 

 organs furnished with a slender 3-jointed palp. These and the very much 

 reduced maxillipedes are the only mouth-organs present ; and the latter 

 are of very simple structure, consisting each of an oval smooth plate, with- 

 out any trace of hairs or teeth. The gnathopoda are relatively small, and 

 the first pair are only about half the size of the second. In both pairs the 

 basos is elongated, and the carpus produced on its inferior margin into a 



