Mr. C. Spence Bate on Diastylis echinatus. 83 



The third somite is slightly broader than the second, and, like 

 it, increases a little in width towards the lateral edge, but curves 

 backwards instead of forwards. The anterior margin is smooth, 

 and the dorsal median line is furnished with a central spine and 

 a small lateral one placed a little anteriorly to it. 



The posterior somite is broader still than the preceding, and 

 increases in extent laterally to nearly two-thirds of its depth, 

 where it is produced both anteriorly and posteriorly into a pro- 

 minent tooth, after which it suddenly decreases to the margin ; 

 dorsally it is armed in the median line with a strong tooth, and 

 laterally with one that is longer and less robust. 



The pleon is as long as the pereion and cephalon together, 

 and therefore half the length of the animal. The first somite is 

 rather deeper than long, and armed upon the dorsal surface with 

 a central upright tooth. The second somite is proportioned like 

 the first, but is furnished with two, parallel, submedian, vertical 

 teeth. The third and fourth are similar to the second ; but the 

 teeth gradually decrease posteriorly. The fifth somite is much 

 longer on the ventral than on the dorsal surface; the dorsal 

 spines are attached to the posterior ridge, and anteriorly directed. 

 The sixth is a little longer than broad, and unarmed. The 

 telson is nearly three times as long as the sixth somite of the 

 pleon, and posteriorly serrated along the dorsal surface. 



The superior antennae are not visible in the perfect animal ; 

 the inferior project a little beyond the extremity of the rostrum. 

 The first pair of pereiopoda are long and powerful, projecting to 

 some distance beyond the extremity of the inferior antennae. 

 The second are shorter, and terminate in a few hairs. The three 

 last are uniform, and about the same length as the second ; they 

 are curved anteriorly, and have the coxse short and as broad as 

 the somites of the pereion to which they respectively belong. 

 The bases are long ; the ischia are short ; the mera and carpi 

 are moderately long and subequal. The propodi are very small 

 and short, and the dactyli are long and pointed. 



The first five somites of the pereion are not furnished with 

 appendages in our specimen. We have therefore little doubt 

 that it is a female. The sixth somite is furnished at the 

 postero-inferior angles with a pair of pleopoda, of which the 

 peduncle is nearly three times as long as the somite to which it 

 is an appendage ; the rami are rather more than half the length 

 of the peduncle, and terminate in styliform points. The telson 

 is as long as the peduncle of the caudal pleopoda, and narrows 

 ventrally after it has passed the terminal outlet of the alimentary 

 canal. 



The length of the animal is about half an inch. It was taken 



6* 



