428 Mr. Newpout on the Anatomy and 



the branchise have the same simple form, but instead of being distributed 

 over the whole surface of the body they are collected into tufts, one on each 

 side of each abdominal segment. In the Hy dropsy ches also they are setaceous 

 and tufted, not merely at the sides of the abdomen, but also at the termina- 

 tions of the caudal styles. In the Sialidce, which come near to the Perlidoe, 

 the respiration of the larva is both caudal and abdominal. Each segment of 

 the abdomen in Sialis has a pair of single, articulated, lateral branchise pro- v 

 jecting from it, while the caudal styles also are respiratory organs, as in 

 Agrion and Hydropsyche. 



In some of the Perlidce, as in Nemoura, Pictet has shown* that the branchiae 

 are not tufted, as in Perla, although they are almost entirely confined, as in 

 that genus, to the thoracic instead of the abdominal segments. They consist 

 of single cylindrical appendages, as in Sialis, and project from the pectoral 

 surface of each of the thoracic segments, three pairs from each. In the true 

 Perlidce \ the branchiae are tufted, are almost entirely thoracic, and are found 

 in the whole of the species, except only in two or three, Perla virescens, P. ni- 

 gra and P. abnormis, Newm., the P. arenosa of Pictet %. In all other known 

 species the sternal surface of each thoracic segment has on each side one or 

 more tufts of these branchial filamentous appendages. Usually each tuft is 

 formed of three bundles or packets of these simple structures, into each of 

 which a minute branch of a tracheal vessel is extended, and around which the 

 blood circulates to be aerated. Pictet has shown that in the larva of Perla 

 bipunctata, as also in other species, the middle one of each three tufts covers 

 the future respiratory orifice or spiracle in the imago. A very similar form of 

 tufted branchiae exists in Pteronarcys (figs. 3 &4). 



The Pupa (fig. 2) of Pteronarcys regalis, the subject of the present commu- 

 nication, was discovered by Mr. Barnston, who favoured me with a specimen 

 of it, but it has not yet been described. It differs both in its general appear- 

 ance and habit from that oi Perla. It is of a dark olive colour, and is covered 

 with slight pubescence. The head is short and triangular, with setaceous an- 

 tennae, almost equal in number of joints to those of the imago. On the upper 

 surface of the head there are three rudimentary ocelli, and the eyes project 



* Monogr. Fam. des Perlides, pi. 53. fig. 7. f Loc. cit. pi. 11. figs. 7 & 8. 



I See Postscript to this paper. 



