SPINOUS GA LATHE A. 



203 



is about as long as the body, slender, and composed of 

 seven annulations ; it terminates in two diverging plates. 

 The last two annulations are of equal size and seem almost 

 blended in one. The terminal plates are armed posteriorly 

 with six bristles in each ; the external ones are short, stout, 

 and pointed, the others are long and slender. The cara- 

 pace is rounded and indented anteriorly, and the eyes are 

 large, sessile, and placed on a festoon of the shield. The 

 antennse are short, terminating in a tuft of bristles. The 

 first pair of natatory claws are three-pointed, and, besides 

 terminating in a tuft of setae, are armed also along their 

 anterior and posterior margins. The posterior claws are 

 in three pairs, the anterior two of which are bifid ; the 

 third or posterior are small, situated at the posterior mar- 

 gin of the shield." 



