II. ('. FALL. 



147 



tures, which are moderately large toward the base, but become finer 

 apically ; interspaces with a single series of punctures (except fer- 

 ruginea), which are, in a few species, nearly as coarse as those of 

 the stria?, but are usually distinctly finer. Presternum usually dis- 

 tinctly longer before the coxa? than the coxal length; more or less 

 roughly punctate, and with a transverse pubescent fossa exterior to 

 the anterior limits of the coxae. Coxal cavities narrowly separated, 

 the coxa? prominent and contiguous or subcontiguous on their free 

 faces. Metasternum of variable length, usually longer between the 

 coxae than the post-coxal length of the first ventral,* but occasion 

 ally subequal to, or even shorter than the first ventral ; punctuation 

 distinct at sides, generally finer and sparser toward the middle, espe- 

 cially posteriorly; median line distinctly impressed in posterior half. 

 Middle coxa?' variably separated. There seems to be a little indi- 

 vidual variation in this particular, but after due allowance lias been 

 made, it is still a character of considerable utility. Abdomen con- 

 sisting of five segments, a sixth frequently visible in the male and 

 very rarely in the female. The first segment is subequal in length 

 to the next three together, these latter much shorter, slightly de- 

 creasing in length, the fifth usually about one-half longer than the 

 fourth, and frequently marked with a median or apical fovea or 

 impression, which varies in the sexes. The femora vary from robust 

 to slender; the second joint of the tarsi is shorter than the first, the 

 third subequal to the first two united. 



The sexes are always easily separable. Aside from the sculpture 

 of the last ventral just alluded to, the males have the first joint of 

 the front tarsi distinctly dilated, and the first joint of the middle 

 tarsi very slightly so ; the front and middle tibia?, and rarely the 

 hind tibiae, are a little curved or bent at tip, or at least more or less 

 sinuate internally before the apex, and with a small mucro or acute 

 denticle at the inner apical angle; the fifth ventral is occasionally 

 shorter, and more broadly rounded or subtruncate than in the female. 



There is little doubt that all the forms mentioned below are valid 

 species, but their tabulation has proved a matter of some difficulty, 

 and its use will not be always satisfactory, unless supplemented by a 

 careful study of the descriptions; even then, a comparison with 

 types will, perhaps, be necessary in difficult cases. 



* This method of comparison of the lengths of the metasternum and first ven- 

 tral segment must be kept in mind in reading the following descriptions. 



TRANS. AM. ENT. -SOC. XXVI. NOVEMBER, 1S99. 



