312 Mr. Westwood on Diopsis, 



Caput rufescens, vertice fusco. Pedunculi oculorum brevissimi (singulo longitu- 

 dinem inter eorum bases baud aequanti) crassissimi, fusco-nigri. Antennce 

 in medio frontis insertse, articulo 3tio rotundato, compresso, apice setigero. 

 Thorax niger, cinereo cinctus. Spinae scutellares 2 rufescentes et 2 latera- 

 les nigrse (inter alarum basin et halteres obviee, at qu^m in prsecedentibus 

 breviores). Alee hyalinse, fascia fuscescenti, transversa, irregulari (prse- 

 sertiin ad marginem internum) pone medium alse posita, hsec fascia ad 

 nervum intermedium transversum extendit et sub nervo 2do longitudinali 

 raagis est obscura ; apex ipse alarum macula fuscescenti angulum basin 

 versus alse formante distinguitur. Pedes rufescentes, femoribus tibiisque 

 ad apicem nigricantibus ; femora antica incrassata, piceo-nigra, femoribus 

 posticis simplicibus. Halteres albi. Abdomen nigrum, immaculatum, cla- 

 vatum. 



Say, in the work first above quoted, described this insect as a Diopsis, and 

 states that he took a single specimen in May 1817, seated on a leaf of the 

 Skunk Cabbage (Pothosfcetida) near the Wissahickon Creek, a few miles from 

 Philadelphia. Subsequently, however, it would seem that he regarded it as an 

 Achias, as Wiedemann states that he received it from him under the name of 

 Achias hrevicornis, adding that, from the form and situation of the antennae, it 

 appeared to him rather to belong to Diopsis. Say afterwards discovered it in 

 profusion in crevices of rocks on the banks of the Missouri, and published a 

 figure of it in the 3rd volume of his American Entomology, under the new 

 generic name of Sphryracephala, distinguished from Diopsis by the shortness 

 of the ocular peduncles, and by having the " antennae inserted in front, the 

 third joint rounded and compressed, setigerous at the tip." Other characters 

 are pointed out as distinguishing this genus from Achias, as the spinose thorax 

 and scutellum ; whence it appears, as Say observes, to be more intimately 

 allied to Diopsis than to Achias. The geographical situation of the species, 

 however, seems to indicate a type distinct from either of these two groups. 



