1. CATOSTOMUS. 13 



none. Gill-rakers well developed, soft, the upper lanceolate, the 

 lower quite membranaceoiis, low folds crossing the bone. Pseudo- 

 brancliiae. Pharyngeal bones sickle-shaped, armed with a comb- 

 like series of numerous comjjressed teeth, the teeth becoming larger 

 and broader towards the lower end of the series. 

 North America; Eastern Siberia. 



The skeleton of Catostonuis has been well described by Valen- 

 ciennes (xvii. p. 433). It is distinguished by the comparative want 

 of solidity, certain bones consisting merely of a network of osseous 

 matter. There is a large and broad fontaneUe on the upper surface 

 of the head, separating the parietal bones and leading direct into 

 the cerebral cavity. The occipital process is, below the anterior 

 vertebrae, enlarged into a bladder-like swelling, which is not solid, 

 but consists of a delicate osseous network only. The prefrontal is 

 advanced to the anterior part of the orbit. The jaw-bones are very 

 feeble, the intermaxillary being reduced to a thin lamella, which 

 docs not descend to the middle of the maxillary. The anterior part 

 of the mandible is horizontal, thin, and slightly dilated. The apo- 

 physes of the four anterior vertebrae are very strong and long. 

 Number of vertebrae 



in Catosfomus teres 29 abdominal, 18 caudal ; 



in Catostomus carpio 21 abominal, 14 caudal. 



1. Catostomus hudsonius. 



Cyprinus catostomus, Forster, P/iilos. Trans. Ixiii. 1773, p. 155, 



tab. 6. 

 Catostonuis hudsonius, Lesueur, Journ. Ac, Nat. Sc. Philad. i. p. 107 ; 



Cuv. S,- Val. xvii. p. 459. 

 forsterianus, Richards. Frankl. Journ. p. 720, and Faun. Bor.- 



Amer. Pise. p. 116 ; Cuv. Si Val. xvii. p. 463. 

 am-ora, Agass. Lake Super, p. 360, pi. 2. figs. 3-4. 



D. 12-13. A. 8-9. L. lat. 100-110. L. transv. 15/23. 



The height of the body is rather loss than the length of the head, 

 which is contained from four times and two-thirds to five times in 

 the total length (-without caudal). Lips very thick, papillose, the 

 lower deeply bilobate. Eye small, behind the middle of the length 

 of the head, the snout being much produced. Suborbital very 

 narrow. There are twelve or thirteen longitudinal series of scales 

 between the lateral line and the root of the ventral fin. Scales on 

 the fore part of the trunk conspicuously smaller than those on the 

 tail. Pectoral fin not extending to the vertical from the origin of 

 the dorsal, which is nearer to the root of the caudal than to the end 

 of the snout. 



Subarctic regions of North America. 



a. Adult, in bad state, has been in cliloride of zinc. Old coLIcction, 



Probably one of the tyjucal specimens examined by Forster. 



b. loung. JFort Halket. Presented by B. K. Eoss, Esq. 



c. Adult : stuffed. Albany River. Presented by Sir J. Richardson 



as Catostomus forsterianus. 



