26 EEV. T. E. E. STEBBING ON THE 



together (see page 9), it must be regarded as distinct from all the earlier known 

 members of the genus.— T. R. R. S., Sept. 1890.] 



Urothoides, nov. gen. 

 1888. Urothoe, Stebbiug, 'Challenger' Amphipoda, Zool. Reports, vol. xxix. p. 824. 



Nearly resembling Urotlioe, Dana, in regard to the antennse, mouth-organs, gnathopods, 

 first and second perseopods, and the pleon. 



Third and fotirth jiermopods having the first, third, and fourth joints much expanded, 

 the third joint more widely than the fourth ; these limbs not armed with long plumose 

 setse as in Urothoe. 



Fiftli permopods having the much expanded first joint strongly produced downwards 

 behind, and with a strongly serrate hind margin. 



The fingers of the peroeopods not nodulous on the inner margin. 



The name is derived from Urothoe, a closely related genus, and elSoe, likeness. 



Urothoides lachneessa. 

 1888. Urothoe lachneessa, Stebbing, 'Challenger' Amphipoda, Zool. Reports, vol. xxix. p. 825, 

 pi. Ivii. 



It is with some hesitation that I now propose a new genus for this recently published 

 species. When originally including it in the genus Urothoe I was not aware how 

 singularly compact a group the existing species of that genus formed, and how 

 intimately connected with one another they were in many minute details. 



Since the ' Challenger ' Report was published I have examined an additional specimen 

 of this species, in which the upper autennte proved to be abnormal. The entire peduncle 

 is stout, the second joint not longer than broad, the third longer than either the first or 

 second, conically produced along two thirds of the first joint of the secondary flagellum. 

 The principal flagellum consists of four joints, the secondary flagellum of three, the first 

 of which is as long as the other two together, and the three together are as long as the 

 principal flagellum. It may be assumed that the malformation results from a coalescence 

 of the third joint of the peduncle with the first one or two joints of the principal 

 flagellum, or it might be more correct to say that the articulations have not been 

 developed so as to produce the usual distinction of these joints. 



The second segment of the pleon is not armed with long plumose setae as in the 

 genus Urothoe, and the rami of the third uropods are also devoid of these ornaments. 

 In the species of Urothoe the outer of tliese rami is perhaps invariably longer than the 

 inner, but sometimes the difiierence is scarcely perceptible, whereas in the present 

 species the difierence between the two rami is very great. 



