BEMBIDIIN.E 175 



not coarse, subequal, the third feeble, four to seven very feeble; an- 

 terior fovea barely behind basal third. Length 1.7 mm.; width 0.63 

 mm. Isthmus of Panama (Colon), Beaumont. . . *colonicus n. sp. 



These two species are closely allied, but colonicus is smaller, still 

 narrower and rather less parallel than austinicus, with relatively 

 somewhat smaller head, prothorax and eyes, and with the anterior 

 thoracic angles more broadly rounded, being in fact completely 

 obliterated; in austinicus they are very obtusely rounded but not 

 entirely obliterated. 



It may be that the Tachys multistriatiis, mentioned but not de- 

 scribed by Motschulsky (Etudes, 1855, p. 13 and 1862, p. 29), may 

 belong to the present genus. 



Tachyura Mots. 



Barytachys Chd. 



There seems to be some confusion in regard to the exact appli- 

 cation of this generic name, but it appears sufficiently evident that 

 it must be identified with the genus subsequently described under 

 the name Barytachys by Chaudoir. At any rate, it is an exceedingly 

 well defined genus, not at all like Tachys, either in habitus or struc- 

 ture, and is in North America the largest genus of the Tachys series. 

 The body is oval, highly polished and very convex, in marked con- 

 trast to the flattened form and usually less polished surface charac- 

 terizing the genus Tachys, and the mentum has no trace of the 

 two foramina of that genus. These foramina, discovered by the 

 writer when describing T. occultator, were used by Mr. Hayward 

 subsequently in his group division of Tachys. In the present genus 

 there are no closed pits or foramina on the mentum, but some- 

 times there are feeble indentations and, in the case of frontalis, 

 which is evidently a true Tachyura, Mr. Hayward has, under inade- 

 quate magnification, mistaken these slight indentations for for- 

 amina and made a separate group of frontalis. I infer this, at 

 least, because of the entire conformity of the body in frontalis with 

 Tachyura in every respect, and because in the drawing of the men- 

 tum, the supposed foramina are not closed but open in front, a 

 condition never observable in the true foramina of Tachys or 

 Pericompsus. 



In Tachyura the head is generally notably small, the eyes well 



