34 GEO. H. HORN, M. D. 



regularly convex and pubescent. The last abdominal segment deprived 

 of hair and more or less ferruginous. In all the specimens before me 

 there is a subtriangular space near the middle of the anterior thoracic 

 margin, smoother and less pubescent. In an examination of the typi- 

 cal specimens, sequalls and gilensis are exactly similar in form, the 

 latter being coated somewhat with earthy matter while the former is 

 clean. The type of sufuralis is in rather bad condition, being densely 

 coated; is broader in form than the others but resembling the fe- 

 male specimens collected in California, and which without doubt are 

 referable to sequalls. Length .20 inch; 5 min. 



Occurs with inoductiis but extends further east than specimens of 

 the latter have been found. 



Sub-Family Elmid^. 



The anterior coxae are rounded and without trochantln. The an- 

 tenuce are slender but slightly thickened at tip. The hind coxge are 

 more widely separated than in the preceding sub-family, and the legs 

 longer and more slender. The genera and species are more numerous 

 and, with the exception of Elmis and Ancyronyx., have representatives 

 on the Pacific Slope. 



The genera represented in our fanna may be thus distinguished; 



Head protected beneath by a prosternal lobe. 

 Antennse 11 jointed. 



Anterior tibise pubescent internally Elmis. 



Anterior tibise glabrous internally Stenelmis. 



Antennse 6-jointed Macronychus. 



Head free; posternum not lobed ; anterior tibiae glabrous internally. 



Antennse 11-jointed Ancyronyx. 



In the above genera are comprised all the species in our fauna. 

 Limnius has been united With Elmis as not being sufficiently distinct, 

 none of the special characters assigned to it having that degree of per- 

 manence entitling them to generic value. The line between a rounded 

 and elongate oval scutellum is not sufficiently distinct, as has already 

 been shown by Dr. Leconte {Proc. Acad. 1866, 380). The degree of 

 sinuation of the basal line of the thorax is equally valueless with the 

 general form; the "tout ensemble" is also a faulty guide, as Elmis, 

 both in Europe and America, appears rather heterogeneous in the as- 

 pect of the different species. The first two genera have rather numer- 

 ous species, the third but two, one of them being Californian, while 

 the one species of Ancyronyx still remains without a congener. 



