150 Trans. Acad. Set. of St. Louis. 



gular sutures less impressed, more approximate toward base; pro- 

 thorax differing greatly in form, about as lorjg as wide, the sides feebly 

 converging from the base to the apex and slightly arcuate; apex more 

 strongly arcuate than the base, the apical angles very obtuse and 

 rounded, a little wider than the head; elytra slightly longer than 

 wide, subparallel, two -fifths wider and nearly one-half longer than the 

 prothorax, paler at the sides than on the disk; abdomen distinctly nar- 

 rower than the elytra throughout. Male with the fifth ventral truncate 

 at apex and unmodified, the sixth much narrower, rectilinearly trun- 

 cate at tip and otherwise unmodified. Length 2.7 mm.; width 0.6 

 mm. Arizona soiiorica n. sp. 



The female in both ochracea and simplex has the apex of 

 the sixth ventral broadly angulate, with the angle more or 

 less rounded. The single specimen of sonorica before me has 

 the apex of the sixth ventral truncate, and, as the sexual 

 modifications are so simple, it may in reality be a female, but 

 in any event it is a remarkably distinct species. The con- 

 cealed ligula of the seventh ventral in Lithocharis, is spatuli- 

 form, narrowed toward tip, and densely clothed with silvery 

 pubescence. 



The Henshaw catalogue (3rd suppl., p. 10) lists a Litho- 

 cltaris debilis Woll. I have been unable to find any such 

 species described. The debilis of Erichson (Gen., p. 625) 

 inhabits Colombia and the description does not correspond 

 with any of our species as given above. 



Medones. 



The multitude of small species of more or less monotonous 

 appearance, composing this group, are rather difficult to 

 classify in a satisfactory manner, owing to the fact that the 

 male sexual characters are usually simple and but slightly 

 varied ; the genus Paramedon, however, offers a very welcome 

 exception in this regard. The group is much more highly 

 developed in America than in Europe, comprising the follow- 

 ing nineteen genera within the limits of the United States, 

 only two of which — Neomedon and Sciocharis — are certainly 

 known to extend for any great distance into Mexico : — 



Gular sutures completely fused, forming a single coarse suture from the 

 ar gulate post-mental piece to the base 2 



