MORGAN HEBARD 283 



as wide, instead of subquadrate, and even weaker blunt tuber- 

 culation of subgenital plate. Much the most important differ- 

 ences are found in the furcula and cerci. In size, form and 

 general appearance this species agrees fully with M . ligneolus 

 Scudder, another very closely related species. The present insect 

 is particularly distinguished from all the forms closely related 

 to gracilipes by the much more elongate furcula. 



Females of these species are most difficult to separate. This 

 sex of hesperus is a little more slender and elongate than females 

 of gracilipes, in every way similar to females of ligneolus except 

 in the very slightly more pronounced lateral carinae of the 

 pronotum. 48 



Type. — c? ; San Luis Obispo, San Luis Obispo County, Cali- 

 fornia. August 21, 1909. (M. Hebard.) [Hebard Collection, 

 Type no. 504.] 



Size small, but, with ligneolus, largest of the species closely related to graci- 

 lipes. Form slender, much as in gracilipes and in M . huporeus here described. 

 Head much as in gracilipes, but with area of f astigio-f acial angle slightly more 

 produced, much as in huporeus, but with frontal costa appreciably wider, as in 

 gracilipes, showing only very slight concavity toward median ocellus. Eye 

 large, over two and one-half times as long as infra-ocular sulcus. Pronotum 

 elongate, disk of almost equal width throughout, median carina well denned 

 and percurrent, lateral carinae distinct though very weakly defined, not sub- 

 obsolete as in gracilipes or fully as weak as in ligneolus, caudal margin of disk 

 broadly obtuse-angulate produced, more produced than in gracilipes. Pro- 

 sternal spine as in gracilipes; elongate, bluntly subcorneal. Tegmina shorter 

 than pronotum, rather broadly oval, feebly overlapping, with apex bluntly 

 rounded. Furcula represented by a pair of slender elongate processes, which 

 diverge at an angle of sixty (to ninety in series) degrees, three and one-half 

 times as long as greatest width, length contained in that of supra-anal plate 

 slightly less than two and one-half times, width about the same in proximal 

 two-thirds and there separated by an interval of nearly equal width, thence 

 tapering to the acute apex. Supra-an al plate shield-shaped; surface with a 

 deep medio-longitudinal sulcus, running through proximal two-thirds, the 

 lateral carinae of this sulcus each with mere traces of a transverse carina 

 externally, mesad on the plate; surface with lateral portions rather strongly 

 concave in proximal two-thirds, beyond which two broad, longitudinal, parallel, 

 short ridges run to the free margin just before the apex. Between the supra- 

 anal plate and the cerci, a portion of a basal plate is extruded, this causing the 

 lateral margins of the plate to be somewhat elevated. Cerci moderately 

 elongate, weakly curving inward, about two and one-fourth times as long as 



48 This feature is probably of little diagnostic value, as the degree of differ- 

 ence noted is easily within the limits of individual variation. 



TRANS. AM. ENT. SOC. XLV. 



