CERAMBYCID/E 365 



and there are enough special features, generally asexual in other 

 parts of the genus, such as the form of the prothorax, to show 

 that the female type described really represents a species distinct 

 from any of the others; they all seem to be rather rare and seldom 

 taken in series. The general characters of the group are a mixture 

 of those of the undulatus and nauticus groups, with some, such 

 as thoracic form and elytral ornamentation, that are essentially 

 peculiar. 



The females of the insignis group resemble Clytus, as represented 

 by planifrons for example, much more closely in form and orna- 

 mentation than they do any of the other types of the genus Xylo- 

 trechus; the males differ greatly from the females in being very 

 pale red-brown in color, with more suffused vestiture and indis- 

 tinct or partially obsolete fasciee, which are so well developed in 

 the female. So, although the species of this group are truly Xylo- 

 trechus, as shown by the peculiar sexual modifications of the head, 

 consisting of two large, very finely sculptured triangular opaque 

 patches on the vertex of the male, which are completely obsolete 

 on the more coarsely sculptured vertex of the female, and, as shown 

 by the frontal carinae, they nevertheless constitute a remarkably dis- 

 tinct and aberrant group of the genus in the sexual diversity referred 

 to above, which is analogous to that even more developed in the 

 genus Calloides. The species of this group in my collection may 

 be defined as follows: 



Elytra with the curved transverse fascia before the middle in the female 

 equal and entire, mounting more narrowly along the suture to a 

 point some distance behind the scutellum, sometimes altogether 

 wanting and always greatly reduced in the male 2 



Elytra as in the preceding, except that the fascia before the middle in 

 the female ends just outside of the median line, the continuation 

 indicated by a small elongate spot near the margin 4 



2 Elytral fasciae in the female white in color and all rather narrow; 

 frontal carinse fused into a tumid oblong punctate glabrous spot; 

 annuli of dense hairs at the apices of all the abdominal segments 

 narrow and white; body black in color throughout, the legs and 

 antennae testaceous. Length (9) 14.5 mm.; width 4.7 mm. 

 Colorado obliteratus Lee. 



Elytral fasciae in the female bright sulphur-yellow in color and much 

 broader. 3 



3 Form more elongate than in the preceding, larger in size, the female 

 black, with the elytra blackish-brown, the legs and antennae rufous; 

 frontal carinse only feebly marked, the intermediate surface flat, 



