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 
Perle, 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 +, 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 bas 
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. Carniol. p. 705. 
ł Introduction, &c. vo]. li. p. 22. 
$ M. Pictet seems to have noticed a somewhat similar shield-shaped process in the females of Perla 
Hanii (pl. 19. figs. 10 & 11) and Perla limbata. 
t Zeitschr. Organ. Phys. t. ii. No. 3. Mar. 1828. 
