382 NEW-YORK FAUNA. 



lar, with a fimbriated margin. A ring of irregularly shaped corneous processes within the 

 oral orifice, and a large isolated double tooth of the same texture on the inferior portion of the 

 mouth. Branchial apertures in an obliquely descending series, valvular ; the first is three- 

 tenths of an inch distant from the eye. Branchial sac pearly white within, somewhat dilated. 

 Sides of the body with numerous vertical rugag. 



The first dorsal commences at a point somewhat nearer the head than the tail ; it is subtri. 

 angular, longer than high, 0"6 long, when it subsides into a low membrane, elevated about a 

 tenth of an inch above the body ; then rises and forms a high rounded fin, in which fibres 

 representing rays may be detected ; again it subsides into a low membrane, extending to 

 within half an inch of the caudal extremity, when it assumes a subtriangular figure, passing 

 round the tail, and is dilated beneath it, forming a rounded fin 0'5 long ; it then subsides into 

 a low cuticular fold, which gradually rises into a fin 0' 1 high as it approaches the vent, where 

 it terminates. A slender thread-like process, 0" 3 long, and apparently tubular, arises from 

 its anterior extremity. Vent near the posterior third of the animal. 



Color. Dark plumbeous above, somewhat paler along the sides, but not separated by a 

 defined line. Irides silvery. All the fins of a pale amber-color. 



Length 4-0 -6-0. 



This small Lamprey I first obtained from Mr. Joseph Mauran of Providence ; and have 

 since received specimens, agreeing with it in every particular, from the Hudson river. It is 

 allied to, but as I conceive very distinct from, the preceding species. 



(EXTRA-LIMIT AL.) 



P. argenteus. (Kirtland, Bost. Jour. Vol. 3, p. 342, pi. 4, fig. 3.) Silvery grey on the sides, with 



irregular series of black dots. A black dot over each branchial aperture. Length 11 inches. Big 



Miami, Ohio. 

 P. tridentatus. (Richardson, F. B. A. Vol. 3, p. 293.) Bluish grey, with irregular yellowish 



patches. Three conspicuous teeth. Dorsals distinct. Length 21 inches. Tributaries of the 



Columbia River. 

 P. lamottenii. (Lesueur, Hist. N. A. Fishes, Op. ined. ; pi. 79, fig. 249, of this work.) Yellowish 



on the sides, with irregular patches of dark brown above ; white beneath. The mouth pectinated 



on its margin. Dorsals continuous. 



