IS0P0D8 OF NOKTH AMERICA. 285 



only, and six on the abdomen, two on the first abdominal .sej^ment, and 

 four on the anterior portion of the terminal segment. 



II. Tlie structure of the feet. — In *S'. vastator the leg's 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 relativel}' 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 pro- 

 portion. 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 seg- 

 ment of the abdomen. 



IV. The presence of numerous tuhercles furnished with hristle-like 

 hairs upon the ahdomen. 



Neither of these points are mentioned in the description of Sphse- 

 ronia vastator. 



In a recent paper, "Gregarious Crustacea from Ceylon," Rev. 

 T. R. R. Stebbing" places Sphxrotria destructor from Florida in the 

 synonymy of Sphaeromu tenehrans Bate from Brazil, and also refers 

 to that species Sph»roma vastator Spence Bate from Madras, and con- 

 siders specimens sent him from Ceylon as belonging to that species. 



In the above description I have pointed out the differences between 

 Sphxroma destructor and Sphxroma vastator. It remains to point 

 out the differences which exist between Sphxronta destructor and the 

 specimens which Dr. Stebbing had from Ceylon. 



The specimens from Florida have the abdomen "thickly tuberculate 

 with low but distinct tubercles, each one surmounted with a tuft of 

 small hairs or bristles." Stebbing says, in reference to this character, 

 that this feature is not of the highest importance, and in some of his 

 specimens can not easily be discerned. In the Florida specimens these 

 tufts are most conspicuous and very apparent in all the specimens. 

 Stebbing further states that in a dorsal view of SpJueroma destructor 

 they are not even indicated in the figure. The drawing was merely an 

 outline drawing, not a finished one, and the statement of the tuber- 

 culate character of the abdomen was made in the text. The above 

 illustration (fig. 295) fully shows this point as well as the difference, 

 in this respect, between the specimens from Florida and those of 

 Steb[)ing. Neither in the text nor in the figure is there any indica- 

 tion of tubercles on the abdomen of Stebbing's specimens. 



The specimens from Florida have the inner plate of the first 

 maxilhi? tipped witli five strong plumose setre and occasionally a sixth 

 one that is feeble; on the outer plate are eleven spines. Stebbing's 



«Spolia Zeylanica, II, Pt. 5, 1904, pp. 16-21. 



