of the antennae: stemmata situated on a very 

 slight elevation : trunk vs^ith the lateral spines 

 conic, blackish: scutel, spines cylindric, seti- 

 gerous at tip : wings hyaline, a band behind the 

 middle, and a semiband before the middle, 

 brow^n; poisers white: abdomen black, imma- 

 culate: feet yellowish; anterior thighs very 

 thick rufous, blackish above and beneath. 



OBSERVATIONS. 



This insect is very rare in Pennsylvania ; a 

 few years since, I obtained a single individual 

 in the month of May ; it had alighted on a leaf 

 of the skunk cabbage, near the Wissahickon 

 creek, a few miles from this city. During my 

 subsequent excursions in pursuit of insects, I 

 had never the good fortune to meet with an- 

 other specimen, until the autumn of 1S19, 

 when with Major Long's party on the Missouri, 

 near the cantonment of the party, on the river 

 shore was a considerable body of rock, on which 

 I was frequently occupied in hunting for organic 

 reliquiae; here, amongst other interesting objects, 

 I had the satisfaction to find the present insect 

 in considerable numbers, lodged, for protection 



PLATE 52. 



