334 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



" On the head between the eyes are a pair of long, forwardly curved 

 spines; the hinder portion of the head is occupied by a rounded median 

 convexity; at the antero-lateral margin of the head is a very short, 

 forwardly directed spine, beneath which the margin is excavated by a 

 semicircular notch. 



"Of the first four thoracic segments the fourth is rather the shortest. 

 Each of the segments bears an outwardly directed spine on each side 

 of the body, corresponding to the pair on the head and of about equal 

 length; those on the fourth segment, although broken, appeared to 

 have been original^ omewhat shorter; close to the lateral margin of 

 each segment, near to its junction with the epimeron, is another long 

 spine projecting outward and over the epimeron. The first segment 

 differs from the succeeding ones in having no separate epimeron, and 

 its lateral margin has two spines instead of one, of which the anterior 

 is the longer; they are both directed forward as well as outward. The 

 fourth thoracic segment has also a second spine, and its postero-lateral 

 margin inclined downward and backward as well as outward. 



"Of the three posterior thoracic segments the first is the largest, the 

 two posterior being equal in size; the epimera of all three segments 

 bears a spine directed outward and at right angles to the longitudinal 

 axis of the body; that of the first of the three segments is considerably 

 the longest; this segment bears also a pair of spines upon the tergum 

 continuous with those on the segments in front, and exactly overlying 

 that on the epimeron. 



"The first three segments of the abdomen are separated by distinct 

 sutures; the first and the third of the segments have a pair of long 

 lateral spines; those of the third segment mark the boundary between 

 it and the caudal shield; the first abdominal segment has a pair of short 

 ventral spines placed on either side of the median ventral line, and 

 upon a ridge which forms the posterior margin of the segment; ante- 

 riorly the segment is bounded by a similar ridge, but without any 

 distinct spines. 



"The caudal shield is oval and convex, with a faintly marked longi- 

 tudinal carina which terminates in a long spine; the lateral margins of 

 the caudal shield are flattened and form a ridge like the brim of a hat; 

 on either side are two long curved spines situated at equidistant inter- 

 vals, and corresponding in position to the lateral spines on the last 

 abdominal segment; the lateral ridge does not terminate in a flattened 

 spine on either side, as in so many other species. 



" The appendages in many cases bear long spines like those upon the 

 body; the antennae, which are very long, have a pair of spines upon 

 the distal extremity of each of the joints; the anterior thoracic append- 

 ages are furnished with a number of stout spines upon the proximal 



