390 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



rami, tapering at tlie base and ciliated, tlie inner about one-tliird longer 

 than the outer. The pleopods are quite naked and destitute of cilia. 



Length 23"™; breadth, 9™°^; breadth of pleon 4™™; length of head 3'™; 

 breadth 4.2-". 



A single siiecimen of this species was dredged by the U. S. Fish 

 Commission, about fifteen miles northeast of Cape Cod!, in 130 fathoms 

 brown mud, September 10, 1879. 



XI.— CYMOTHOID.^. 



Head produced anteriorly over the ])asesof the antennulte ; maxillipeds 

 few-jointed, operculiform ; mandibles palpigerous; mouth suctorial; legs 

 armed with strong curved dactyli; epimera distinct behind the first 

 thoracic segment ; telson large and flattened ; pleopods not ciliated ; 

 nropods articulated near the antero-lateral angles of the last segment, 

 and composed of a more or less flattened basal segment bearing two 

 flattened rami; habit parasitic; body often unsymmetrical by distortion 

 in the adults. 



This family is represented within our limits hy three genera and as 

 many species. They are parasitic in habit, usually on fish, and fix them- 

 selves by their strongly-curved claws to their host, often within the 

 mouth, or about the branchial cavity, and frequently become distorted 

 when fully grown. In all our species the head is small, and has the 

 anterior margin produced, concealing the bitses of the antennulse and 

 the antennae. The head is three-lobed behind, and the first thoracic 

 segment is adapted to it. The antennulae and antennfe are both short 

 and tapering, without very evident distinction into peduncular and 

 flagellar segments. This distinction is, however, usually more or less 

 evident on examination. 



The epimera are well separated, except in the first segment, and may 

 be projecting and conspicuous. The legs are of nearly the same form 

 throughout, but increase in length and become more slender posteriorly.* 

 The basal segments are in some genera enlarged and flattened, but not in 

 ours ; the joint between the basis and ischium is strongly flexed, and 

 the segments, at least beyond the ischium, to the dactylus, are short and 

 capable of but little motion on each other. The dactylus is strongly 

 curved and admirably fitted for firm attachment to the host on which the 

 animal may be living. In our species the legs, in the natural position, 

 are concealed in a dorsal view beneath the body of the animal, to the 

 under surface of which they are appressed, the first three pairs being 

 directed forward, and the last tliree backward, as represented in plate 

 X, fig. G6. 



The pleon in our si)ecies is not suddenly narrower than the thorax, 

 as it is, however, at least in the adults, in some genera belonging to this 

 family. The segments of the pleon are distinct, the last one scutiform 



"lu^r/^/s^oneSchiodte the seventh pair of legs "reach to the extremity ofthe tail and 

 are slender, compressed cra^wlinglegs, with a small, almost rudimentary, straight claw." 



