AMERICAN COLEOPTERA. 89 



Sub-Family II. — Helodid^. 

 This sub-family differs principally from the preceding in the ab- 

 sence of trochantin to the anterior coxae. The species are all of 

 rather small size and are found on plants near water. The genera 

 are capable of division into tribes in the following manner : 



Tarsi with the fourth joint very small, third lobed beneath. (PI. I, fig. 6 a). 



PriLODACTYLINI. 



Tarsi with the fourth joint as large or larger than the third. 



Posterior coxse very large .... Eucinetini. 



Posterior cox£e at most moderately dilated internally. 

 Claws without membranous appendage. 

 Front moderately broad, presternum very short before and very narro':v 



between the coxse Hei.odini. 



Front narrowed by the insertion of the antennae, presternum distinct 



before and between the coxse Eubriini. 



Claws with membranous appendage arising from the base of each claw 

 and as long as it. (PI. I, fig. 16 c). 

 Front narrowed by the insertion of the antennae Placonychini. 



In the above tribes the Ptilodactylini seem to lead very naturally 

 from Anch^tarsus of the preceding tribe. Thomson detects a rela- 

 tionship between Eucinctus and Catops which entirely escapes me, 

 although the structure of the under side and legs has some resem- 

 blance to Mordclla, without however any special relationship. The 

 Eubriini and PlaconycMni have more than a resemblance to the 

 Parnidae, the anomalous Psephenus of that family affording a close 

 link with the present. The last named tribe by its appendiculate 

 claws approaches in another direction the Melyridae, but the affinities 

 Otherwise are not well marked. 



Tribe I. — Ptilodactylini. 



Head deflexed, concealed from above by a moderate prolonga- 

 tion of the thorax. Clypeus separated from the front by a dis- 

 tinct suture. Prosternum moderate in front of the coxae and pro- 

 longed between them but less prominent. Anterior coxae without 

 trochantin. Tibiae not carinate on the outer edge. Tarsi above 

 convex, the first joint of the posterior longer than the others, the 

 fourth on all very small and almost concealed within the third, 

 second and third lobed beneath. Claws broadly toothed at base. 

 Tibial spurs moderate on the two anterior pairs, elongate on the 

 posterior. 



The above characters excepting the small fourth tarsal joint, apply 

 to the limited representation of the tribe in our fauna rather than to 

 the tribe as a whole. One genus occurs in our fauna remarkable for 



TRANS. AMER. ENT. SOC. VIII. (12) MARCH, 1880. 



