9 1 2 ZOOLOGY INSECTS. 



The species above described is the dwarf of this genus ; the smallest 

 species known, Ft. proteus, having twice the length of Pt. regularis and PL 

 ladia. The gills are well visible in the alcoholic specimens of Pt. ladia, 

 twenty-six pairs in number, to wit, six between the head and the prothorax; 

 six between the prothorax and the mesothorax; six between the meso- 

 thorax and the metathorax ; two between the posterior feet ; and six on the 

 basal segments of the abdomen. The maxillary palpi are longer than the 

 mouth, the basal joint short, the other long, thicker at the tip ; the labial 

 palpi are similar. The palpi show a similar formation as the apical joint in 

 the phryganideous genus Hydropsyclie. The external membrane is cut or 

 split in a somewhat spiral manner, so as to give to every joint the appear- 

 ance of a large number of small joints imperfectly soldered together. This 

 formation of the palpi belongs to all the species of Pteronarcys, and is excep- 

 tional for this genus only in the whole family of Perlina. 



These two small species agree in all characters with the larger species, 

 at least so far as the females are concerned, as the males are still unknown. 

 The wings are divided into quadrangular cells, perhaps a little more regular 

 than in the larger species. The venation of Pteronarcys seems to resemble 

 the most the remarkable fossil genus Miamia. 



Secured at Fairplay and Twin Lakes, Colo., by Dr. J. T. Rothrock. 



PTEKONAECYS CALIFORNICA, Hagen. 



Pteronarcys californica, HAGEN, Synop., 1C, p. 5. Id., Proe. Bost. Soc. Nat. Hist., xv, 

 US-L Id., U. S. Gfiol. Surv. Terr., 1873, 573. 



A full description is given in the monograph of this genus in the quoted 

 proceedings. 



HAB. California ; Washington Territory, between Rock and Cascade 

 Rivers; Lake Winnipeg (Kennicott); Ogden, Utah, from a river tributary 

 to Great Salt Lake, in June (C. Thomas). Nymphse from the San Luis Val- 

 ley, Colorado. 



According to McLachlan's statement, the wings of the California speci- 

 mens are very smoky and opaque ; perhaps they were darkened by the car- 

 bolic acid used by the collectors. Pt. californica is a decidedly western 

 species. Pt. biloba, from Trenton Falls, N. Y., a species as yet only repre- 



