312 Mr. Westwoop on Diopsis, 
Caput rufescens, vertice fusco. Pedunculi oculorum brevissimi (singulo longitu- 
dinem inter eorum bases haud zequanti) crassissimi, fusco-nigri. Antenne 
in medio frontis insertz, articulo 3tio rotundato, compresso, apice setigero. 
Thorax niger, cinereo cinctus. Spine scutellares 2 rufescentes et 2 latera- 
les nigree (inter alarum basin et halteres obvize, at quàm in praecedentibus 
breviores). Ale hyaline, fascid fuscescenti, transversa, irregulari (præ- 
sertim ad marginem internum) pone medium alc posita, hzc fascia ad 
nervum intermedium transversum extendit et sub nervo 2do longitudinali 
magis est obscura; apex ipse alarum macula fuscescenti angulum basin 
versus alæ 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 (Pothos feetida) 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 brevicornis, adding that, from the form and situation of the antenne, 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 * antenne 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. 
