26 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



There are usually three pairs of uropods present. These 

 appendages are never very movable and are always directed 

 posteriorly, and are closely approximated. Like the pleopods 

 they are made up of an unjointed peduncle and two rami, although 

 in the Orchestiidae, and in the genera Unciola, Stenothoe, Siphon- 

 cecetes, Corophium, and Ericthonius; the terminal pair is uniram- 

 ous. The rami are usually uniarticulate although the outer one 

 may exhibit also a small terminal joint. The terminal uropods 

 often dififer greatly from the preceding pairs in size and form. 

 In Ampelisca and the Gammaridse they project considerably 

 beyond the others. In Melita the inner ramus is reduced to a 

 mere scale-like rudiment while the outer one is biarticulate. 

 Usually both the peduncle and the rami bear strong spines along 

 the upper margin and at the tip. In Leptocheirus, Microdeutopus, 

 and Grtihia, the peduncle is prolonged beneath the attachment of 

 the rami to form a long, slightly upturned, spiniform process. In 

 Unciola the peduncle is produced into a lobe as long as the single 

 ramus. 



The rami may be lanceolate or flattened, as is seen best in 

 the Gammaridas, or they may be cylindrical or conical with re- 

 curved spines at the apex, as in Jassa, Ischyrocerus, Grubia, and 

 Amphithoe. 



In Cheliira the uropods are highly specialized. The first pair 

 are of the typical form, but the second pair lie well on the dorsal 

 side of the abdomen ; the peduncle bears a very large plate-like 

 expansion medially and the rami are scarcely longer than wide; 

 the terminal uropods are very large, with the outer ramus ex- 

 tremely long, especially in the male, and the inner ramus minute. 



Owing to the extremely rudimentary condition of the abdomen 

 in the CaprcUidea, the appendages are greatly reduced. In 

 ^ginella the first pair of appendages are biarticulate and the sec- 

 ond pair are uniarticulate. In Caprella the males have a biarticu- 

 late pair in front and a thick uniarticulate pair behind. In the 

 females the limb-like (first) pair are reduced to simple 

 eminences bearing a, few setse. 



Sense Organs. 



Besides the eyes, which have already been discussed, the sense 

 organs of the Amphipoda consist of various filiform and special- 



