included in the genus Tropisternus. 105 



17. Tropisternus crassus, Sharp. 



Sharp, Biol. Cent. Am., i., pt. 2, p. 55. 



Guatemala. 



Very closely allied to T. chalybeus, and approached on 

 one or more points by some of the varieties of that 

 species, but of shorter and broader form, with the legs 

 shorter, and the pubescent area on the femora compara- 

 tively a little larger. 



Group 6. Sternal spine not flat, acuminate, of moderate 

 length, extending nearly or quite to 2nd ventral suture ; 

 pubescent area of posterior femur of moderate extent 

 (occupying about one-fourth of the whole area of the 

 lower face) ; last ventral segment unarmed. (Species 

 18 and 19). 



The two species of this group are not closely allied. 

 T. nitens is variable in size and form, and is more likely 

 to cause difficulty in its identification than any other 

 species of the genus, owing to the superficial resemblance 

 it possesses to species of other groups. T. ovalis, on 

 the other hand, is, by its small size and peculiar form, 

 more readily distinguished at a glance than any other 

 species of the genus. In both species the epipleural 

 margin is punctate even at the base. 



18. Tropisternus nitens, Cast. 



Cast., Hist. Nat., ii., p. 54. 



From Mexico to Rio de Janeiro. (Mexico ; Guatemala ; 

 Colombia ; Venezuela ; Demerara ; Bahia ; Rio de 

 Janeiro ; Santa Cruz). 



In this species the 6th joint of the antenna is slightly 

 larger than in most others of the genus, but is a good 

 deal smaller than it is in T. ovedis. It is one of the 

 most abundant species of the genus, and varies much ; 

 the length is between 6^ mm. and 10| mm. ; the colour 

 of the upper surface is usually shining black, but some- 

 times is strongly metallic ; the form is rather narrow, 

 and sometimes attenuate behind, sometimes rounded. 



