244 Trans. Acad. Sci. of St. Louis. 
to the rounded base; elytra small, distinctly longer than wide, scarcely 
more than a fourth wider than the prothorax and very slightly longer, 
the sides subparallel, the basal angles unusually broadly rounded; 
abdomen broad, at base but little narrower than any part of the elytra, 
distinctly wider posteriorly. Male with the sixth ventral moderately 
broad, arcuato-truncate, the acutely triangular notch small, somewhat 
deeper than wide with its sides straight, its posterior angles obtuse and 
slightly rounded with the opening between a fourth and fifth as wide 
as the segmental apex. Length 3.8 mm.; width 0.6mm. California 
(Sta. Cruz to Humboldt Co.).....e.esecsecceseess+-Californicus Aust. 
The coloration of the head in mature individuals appears 
to be sufficiently constant to be utilized as a dichotomous 
character, for in those species represented before me by large 
series, such as discopunctatus, longiusculus, cinctus, prolixus, 
inconstans and others, Ihave found it to be unvarying, no 
specimen of discopunctatus, for example, ever has the head 
‘in the least dusky. The only doubt that need arise may be 
due to immaturity of the black-headed species, but, as the 
head and abdominal apex seem to be the first somites to 
mature, there will probably be but few cases of uncertainty 
even from this cause. The genus is abundantly represented 
in New England and the Atlantic regions generally and the 
forms run together rather closely, forming a difficult study. 
Trisignatus Boh., is probably the same as longiusculus Mann., 
as the latter occasionally has a large feeble internally rounded 
nubulosity on each elytron, which may sometimes become 
more distinct. | 
In considering the species of the table in accordance with 
their natural affinities, it should be stated that prolixus, 
americanus, linearis, strigilis, spectrum, and zuni form one 
group, cinctus a very distinct group by itself, as shown by 
general form and by the nature of the secondary sexual 
characters, binotatus, ornatellus, inconstans and simulans an- 
other for the same reason, discopunctatus, fusciceps, brevi- 
pennis, arizonianus, tenuiveniris, similis, sectator and longi- 
~ usculus another, and, finally, robustulus and californicus form 
a remarkably isolated group, peculiar to the true Pacific 
coast fauna. Discopunctatus is very abundant everywhere 
east of the 100th meridian and represents in these regions 
the Pacific coast longiusculus, which has much larger elytra, 
