included in the genus Tropistemus. • 111 



Group 8. Upper surface with a yellow margined cincture ; 

 epipleural margin rather finely punctate, the punctures 

 distinct, however, even at the base. (Species 28 

 and 29). 



Two species are included in this group ; they do not 

 differ in any important respect from Group 7, but I have 

 separated them because the yellow marginal band gives 

 them a rather different appearance. 



28. Hydrophilus lateralis, Fab. 



Fab., Syst. Ent., p. 228. 



America, North and South, including the Antilles. 

 United States, from New York southwards, abundant ; 

 Mexico and Central America, abundant ; Cuba, Antigua, 

 St. Thomas ; Eio Janeiro, Constancia, Buenos Ayres, 

 Chili. 



In this species the form is rather slender and elongate, 

 and the upper surface shining, closely, very finely, and 

 evenly punctate ; the yellow cincture is subject to a good 

 deal of variation in its width and regularity, but usually 

 is narrower on the wing-cases than on the thorax, be- 

 coming on the former narrower as it proceeds backwards, 

 so that it nearly entirely disappears before reaching the 

 suture at the apex ; the systematic punctures on the side 

 of the thorax are fine and form a rather short irregular 

 line ; the epipleural margin is narrow, so that the punc- 

 tures on it are not coarse, but they are quite distinct 

 from the shoulder backwards ; the sternal spine is rather 

 elongate and slender, and the apical ventral segment is 

 either unarmed or bears a carina or plica of variable ele- 

 vation and length ; the pubescent area at the base of the 

 hind femur is quite small ; the legs are yellow, with the 

 femora infuscate to a variable extent. The male has a 

 distinct tooth on the inner claw of the middle and pos- 

 terior feet, and this is the only certain external sexual 

 mark I can detect. 



The species varies much in the breadth and regularity 

 of the yellow cincture on the head, thorax, and wing- 

 cases ; sometimes it is broader on one or other of these, 

 and sometimes, but rarely, on the wing-case it becomes 

 rather broader and more irregular at the apex. The 

 armature of the last ventral plate also varies greatly; 



