444 Mr. Newport on the Anatomy and 



The male of this species, in which we may expect to find these parts much 

 more developed, is unknown. The female of a third species, P. Proteus, 

 differs both from P. regalis and P. biloba. Instead of having the margin of 

 the eighth segment notched, it has it slightly elongated and rounded in the 

 middle, and it is not divided longitudinally into two plates. In this respect 

 it somewhat resembles the male P. regalis. It is thus evident that the mere 

 presence or absence of a process to the eighth segment is not a character 

 peculiar to either sex ; as a rounded margin to this segment exists in some 

 Perlce, as well as in Pteronarcys Proteus. The distinctive character of the 

 sexes in Pteronarcys is the length of the process. The notched or toothed 

 margin in the female P. regalis is elongated into a bifid appendage in the 

 male ; whilst the slightly developed part in the former sex of P. Proteus also 

 is enlarged into a long, thick, spoon-shaped structure in the latter, very 

 different in shape from the corresponding part in the same sex of P. regalis. 

 The view entertained by M. Pictet, that the appendage to the eighth segment 

 is characteristic of the female Pteronarcys, and that it is designed for the 

 purpose of retaining her eggs, thus appears to be incorrect as regards this 

 genus. Nevertheless, it may be valid as regards Perla, in which the struc- 

 ture is absent in the male. Scopoli *, Suckow f, and Curtis have remarked 

 that the female Perla cephalotes carries her eggs in a mass, inclosed in a 

 membrane, at the apex of the abdomen ; and there is a specimen of Perla 

 abnormis in the collection of the British Museum, taken by Mr. Barnston in 

 Canada, which has a rounded mass of small black eggs attached to the eighth 

 segment, like the egg-capsule in Blatta. Another observer, Mr. Westwood %, 

 has noticed a similar mass of eggs borne by a female Eusthenia diversipes. 

 Thus the view is correct as regards Perla and Eusthenia, although quite un- 

 supported with reference to Pteronarcys. The female of Perla abnormis has 

 the whole margin of the segment semicircular, and it is deeply incised in a 

 diagonal direction on each side, so as to form a kind of lid or valve, from 

 behind which the eggs in Mr. Barnston's specimen project §. The males 



* Ent. Camiol. p. 705. f Zeitschr. Organ. Phys. t. ii. No. 3. Mar. 1828. 



t Introduction, &c. vol. ii. p. 22. 



§ M. Pictet seems to have noticed a somewhat similar shield-shaped process in the females oi Perla 

 Hanii (pi. 19. figs. 10 & 11) and Perla limbata. 



