ON THE SYNONYMY OF THE PERLITES. 85 



Perla bicaudata, Pictet ; 'Annales des Sciences Naturelles,' vol. 

 xxviii. p. 58, tab. vi. jf. 6 — 7; but I believe not of eithe'r of the 

 authors as quoted by M. Pictet. 



I make the assertion that my Isogenics nubecula and M. 

 Pictet' s Perla bicaudata are identical, on that author's own 

 authority ; who, not having examined the Linnaean specimen, 

 expressed his opinion when in England, that the insect in 

 question was the Phryganea bicaudata of Linnaeus, which I 

 think I have shown above to be perfectly distinct. 



Body dark brown ; head and prothorax with a longitudinal ochreous line. 

 Forewings hyaline, with a small oval spot of a dark brown colour on the 

 costal margin, situated about two thirds of the distance from the base to 

 the tip, hind wings beautifully hyaline, iridescent. 



Common in Herefordshire, Worcestershire, and Notting- 

 hamshire. In most cabinets of British insects. 



Sp. 3. I sog, frontalis. (Corp. long. .775 unc. alar, dilat. 1.425 unc. 

 „ „ Newman; 'Entom. Magazine,' vol. v. p. 178. 



Perla bicaudata, Kirby; ' Fauna Boreali- Americana,' part Insects, 

 p. 252. 



Brown, having the anterior part of the head between the antenna yellow, 

 at the back of the head is a second yellow marking, and the prothorax has 

 a yellow longitudinal line ; the wings are hyaline ; the forewings have a 

 very slight brown costal spot in the same situation as the preceding species. 



Inhabits North America. Several specimens (donor R. Fos- 

 ter) are in the cabinet of the Entomological Club. 



Sp. 4. Isog. microcephala. (Corp. long. .8 unc. alar, dilat. 1.5 unc.) 



Perla microcephala, Pictet; 'Annales des Sciences Naturelles,' 

 vol. xxviii. p. 59, tab. vi.ff. 4, 5. 



Black : head spotted with yellow and narrower than the prothorax, which 

 is very short, wider posteriorly, and marked with a yellow longitudinal line; 

 the femora are brown, the tarsi yellow spotted with black : the wings are 

 hyaline, with light clouds of a brown tint. 



Inhabits France, Switzerland, &c. There are several spe- 

 cimens in the cabinet of the British Museum. 



Sp. 5. Isog. infuscatus. (Corp. long. .55 unc. alar, dilat. 1.6 unc). 

 „ „ Newman, ' Entom. Mag.' vol. v. p. 499. 



The head is entirely brown and wider than the prothorax, in which, how- 

 ever, it is deeply immersed : the prothorax is much wider anteriorly than 

 posteriorly ; it is dark brown, with the exception of a very slender, pale, an- 

 terior margin : the disks of the pro- and mesothorax are brown, their lateral 

 margins inclining to yellow: the wings are entirely opaque and nearly black, 

 with the exception of the costa, which in all the wings is yellow. 



Inhabits the East Indies. A single specimen is in the ca- 

 binet of the Rev. F. W. Hope. 



