Description of a New Species of SpJiseroma. 107 



animal was rolled up like a ball." Notwithstanding the close resemblance 

 in habits and appearance of this species, as described and figured, to the 

 present one, there are four points of difference : 



I. The number mid arrangement of the tubercles in the two species. In S. vas 

 tator four tubercles are described on each of the last three segments of the 

 thorax, and only two are figured on the anterior portion of the pleon. 

 In the species under discussion, however, there are four tubercles on the 

 seventh segment of the thorax only and six on the abdomen, two on the 

 post-abdomen, and four on the anterior portion of the caudal shield. 



II. The structure of the feet. In 8. vastator the legs of the first three pairs 

 are not proportionately as long as those of the present species. The merus 

 is differently shaped, not being cylindrical in that species, and is relatively 

 shorter. Although Spence Bate mentions no dissimilarity in structure in 

 the legs of the fourth and fifth pairs, still a difference is shown in the cut 

 in the formation of the merus. With our species the difference in these 

 two pairs of legs is merely in proportion. There is a greater resemblance 

 in the sixth and seventh pairs of legs of the two species. 



III. The upcurved margin of the posterior half of the terminal segment of the 

 abdomen. 



IV. The presence of numerous tubercles furnished with bristle-like hairs upon 

 the abdomen. 



Neither of these points are mentioned in the description of Sphseroma 

 vastator. 



