142 Trans. Acad. Sci. of St. Louis. 
rather a singular circumstance in view of the notable external 
similarity of this species to aemula; third the rounded 
sinus of famelica, and, fourth, the pointed sixth segment 
with very minute notch observable in ambigua, rubida and 
probably fragilis, these last species differing from the others 
also in the much more widely diverging gular sutures, less pro- 
nounced difference between the first and second joints of the 
hind tarsi and more depressed form,— so that they probably 
constitute at least a subgenus. The grouping in the table is 
arbitrary and based solely upon general habitus, in order to 
facilitate identification. The ambigua group, for example, 
contains several discordant elements. 
Of the species allied to collaris, as given above—these being 
likely to prove most troublesome to the identifier,— it may be 
stated in short that gracilicornis is distinguished by its longer 
antennae, oregonensis by its larger and broader elytra, follax 
by the strong pronotal sculpture, vagans by sexual differences 
in the male and rather more slender form, and, habdilis, by 
its almost completely non-incrassate antennae and very feeble 
elytral sculpture. There are other forms which appear to be 
offshoots of the collaris stem, but at present it would serve 
no useful purpose to describe them. Collards is an abundant 
species, widely diffused through the northeastern parts of Ame- 
rica and is one of the few plicate Lathrobiids thus far known 
to occur in the New England states. 
Tricolor was stated some years ago by Dr. Horn to bea 
synonym of ventralis Lec., but I am by no means certain of 
the correctness of this synonymy, the unique type of ventralis 
differing considerably in color. Additional comparisons are 
desirable. The above description is drawn from the original 
types of tricolor. 
Microlathra 1. gen. 
.The few species assignable to this genus are readily dis- 
tinguishable from those of Lathrobiella by the more parallel 
form, uniformly pale coloration, larger subpyriform head, with 
very small eyes and a general habitus which strongly recalls 
