Affinities of Pteronarcys regalis. 447 
POSTSCRIPT. 
Descriptions of some American Perlidze, together with Notes on their Habits. 
Read June 20th, 1848. 
Tue anatomical facts shown in the paper on Pteronarcys and its affinities, 
already communicated to this Society, prove that the insects of that genus 
differ greatly from those of Perla, and others of the same family; and that 
instead of being placed at the head of the tribe, according to the views of 
M. Pictet, they more naturally follow Perla, and precede Capnia and Ne- 
moura, both which they resemble in the form of the alimentary canal. On 
the other hand, they seem to be connected with the former genus by means 
of Perla infuscata, which has the eighth abdominal segment developed as in 
Pteronarcys. The true Perle approach the Orthoptera, through the Blat- 
tide, in the structure of the alimentary canal, in the form of the manducatory 
organs, in the membranous spots at the base of the antennze, and in the habit 
of carrying their eggs attached in a mass to the under surface of the body,— 
the subgenus Acroneuria of Pictet, the Perla abnormis of Newman, being 
placed at the head. _ 
The species Perla arenosa of M. Pictet most certainly is the Perla abnormis 
of Mr. Newman. The former gentleman states that he has examined three 
female specimens of his insect, one from Philadelphia, sent to him from the 
museum at Paris; a second from Pennsylvania belonging to the Berlin mu- 
seum; and a third to the museum of Neufchatel, also obtained from the 
United States. The original specimen of Perla abnormis, which M. Pictet 
knows only from description, was obtained from North America; and Mr. 
Barnston took this species on the Albany River in Canada. Since the return 
of this gentleman to Canada I have received from him some specimens of a 
Perla in spirit for dissection, taken at Tadousac, on the northern shore of the 
River St. Lawrence, which on comparison with the original specimen of Perla 
abnormis now in the British Museum, have proved to be that species ; and on 
comparing the whole of these with M. Pictet's figure and description of P. are- 
VOL. XX. > 3N 
