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 3.3 mm. ; width 0.6 mm. California 

 (Sta. Cruz to Humboldt Co.) californicas 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 discopu7ictatus , longiusculus, cinctus, pr-olixus, 

 inconstans and others, I have found it to be unvarying, no 

 specimen of discopunctaius^ 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, ornafellus, inconstans and simulans an- 

 other for the same reason, discojmncfatus, fuscicep>s, brevi- 

 pennis, arizonianus, tenuiventris, 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, 



