included in the genus Tropisternus. 107 



20. 'Tropisternus concolor, Sharp. 



Sharp, Biol. Cent. Am., i., pt. 2, p. 57. 



Mexico and Guatemala. 



This species, hy the deep coarse punctures on the epi- 

 pleural margin, resembles T. nigrinus, but T. concolor is 

 of shorter and broader form, more rounded behind, with 

 the sculpture of the upper surface excessively fine, and 

 the systematic punctures at the side of the thorax are 

 more concentrated, for, while in T. nigrinus they form a 

 moderately short line, in T. concolor they are nearly or 

 quite concentrated into a group placed in a small round 

 depression. 



21. Hydrophilus elUpticus, Lee. 

 Lee, Proc. Ac. Phil., 1855, p. 368. 



North America (New Mexico, California, Utah). 



This species is readily distinguished from its North 

 American allies by the fact that the systematic punc- 

 tures on the side of the thorax are much reduced, there 

 being only two, placed very near one another (or even 

 amalgamated), but occasionally at a distance on one or 

 both sides of these may be seen another much finer 

 puncture, marking the beginning or end of the series as 

 it exists in other species. The form is broader and more 

 obtuse behind than it is in H. californicus and H. sub- 

 Icevis ; the upper surface is very polished, and its sculp- 

 ture extremely fine ; the punctures on the epipleural 

 margin are very distinct from the shoulder backwards ; 

 the sternal spine is formed much as in H. californicus ; 

 on the last ventral segment there is only a very obscure 

 carina, and the pubescent area at the base of the pos- 

 terior femur is small ; the legs are dark, but marked 

 with yellow. There appears to be little or no sexual 

 difference in the sculpture of the mentum. 



I have seen only three individuals, from California 

 and Utah. 



22. Tropisternus nigrinus, Boh. 

 Boh., Eugen. Besa, Coleoptera, p. 22. 



Brazil ; Bio Grande, Parana, Corrientes ; Monte 

 Video (fide Boheman). 



TRANS. ENT. SOC. 1883. — PART II. (JUNE.) K 



