380 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



is furnished with a few bristles near the base, and its upper edge is 

 armed with minute denticles; it is movable and ordinarily concealed 

 behind the mandible. On the external surface, just above the origin 

 of the palpus, each mandible bears two elevated, conical, obtuse tuber- 

 cles. The palpi are slender, the second segment longest and hairy on 

 the margin beyond the middle, the last segment slender and curved, 

 with the usual hairs or slender bristles along the inner curvature. 



The second and third thoracic segments are a little shorter than the 

 others, which are of about equal length. The fourth and fifth segments 

 are widest. The first segment is produced at the sides around the head 

 so as to very nearly attain the anterior lateral angles of the head, and 

 often so as to obscure the lower margin of the eyes. The epimeral su- 

 tures are scarcely distinguishable in this segment, but evident in the 

 following segments. The epimera are rounded behind as far as th« 

 fourth, but the fifth is slightly angulated, and the sixth and seventh 

 acute and produced backward beyond the margin of the corresponding 

 segment. The first pair of legs are short and stout, and well armed 

 with spines and bristles ; the basis is of the ordinary form ; the ischium 

 is nearly triangular, having the upx^er margin much produced in the 

 distal portion and bristly ; the merus is expanded in a somewhat similar 

 manner, but the angle is bent forward beyond the short carpus over 

 the base of the propodus ; the opposite or lower margin of the merus 

 is armed with short stout spines ; the carpus is short and small and 

 possesses but little motion on the propodus, which is robust, somewhat 

 curved, and bears a strong short dactylus. The second and third pairs 

 of legs resemble the first x)air, but the carpus increases somewhat in 

 size, and there is more motion in its articulation with the propodus. 

 They are directed forward, while the remaining j)airs are usually 

 directed backward and are more flattened. The fourth pair of legs 

 are short like the first three (pi. X, fig. 02 h), but, except in size, resem- 

 ble the following pairs. They are well i^rovided with bristles in tufts, 

 and along the margins of the segments, and especially the merus and 

 two adjacent segments, are armed with long stout spines. The pro- 

 podus is straight and much more slender than the carpus. The fifth 

 and sixth pairs of legs increase in size, and the propodus especially be- 

 comes more elongated, but the seventh pair are a little smaller than the 

 sixth. 



The pleon is scarcely narrower at base than the last thoracic segment, 

 and the first segment is often nearly concealed by the last thoracic. The 

 fifth segment is longer on the back but shorter at the sides than the 

 preceding segments. The last segment, or telson, is triangular with the 

 ciliated apex truncated and emarginate or notched at the end of a short 

 median furrow at the tip. The uropods (pi. X, fig. 63) slightly surpass 

 the telson and are strongly ciliated ; the inner ramus bears also a few 

 spines near the tip ; the basal segment has the inner angle produced 

 along the margin of the inner ramus, which is broad and expanded 



