ZOOLOGISCHE MEDEDEELINGEN — DEEL IL 



in both species is remarkably expanded by a membranous, though tough, 

 expansion of the hind margin, which is very well represented in the 

 quoted figures of Hoek and Chevreux in the case of 0. bottae and by 

 Sars (Crustacea of Norway, v. I, Amphipoda, 1895, pi. 10) in the case 

 of 0. gammarellus ; a similar expansion occurs at the hind margin of the 

 preceding joint. At the outer side of the base of these rather pellucid 



Fig. 1. First gnathopod of male of Orcheslia bottae H. Milne-Edwards. Magn. 28. 



Fig. 2. Part of first gnathopod of female of Orcheslia bottae. Magn. 28. 



Fig. 3. Part of first gnatopod of female of Orchestia gammarellus (Pallas). Magn. 28. 



processes there is a row of large spines, projecting beyond the margin 

 of the expansion ; also at the inner side of the base there are some spinules. 

 This disposition is shown by all my specimens of both species, but the 

 only figures in which the spines inserted at the base of the expansions 

 are depicted in the same way are that of Hoek (f. 8), of Chevreux (f. 3) 

 aud of Delia Valle (pi. 1 5 f. 42) in the case of the carpopodite ; neither 

 of them corresponding as to the spines on the hind margin of the pro- 

 podite with my finds, but representing these as rather irregularly placed. 

 In the females (f. 2 and f. 3) the expansions on carpo- and propodite 

 of the first gnathopod are absent, but the hind margin of the carpopodite 

 projects at a right angle, and the propodite is quadrangular, with a 

 rounded projection at the distal angle of the hind margin; the distal 

 margin of this joint has three bundles of tactile spines agreeing in shape 

 with those on the joints of the antennae. All the spines of the gnathopods, 

 as well as those of the other pereiopods, have a thick subterminal hair 5 

 in the same way as in Talorchestia brito. The females of 0. bottae and 



