202 SALMONID^. 



the total length (without caudal), the length of the head not quite 

 five times ; snout asl ong as the diameter of the orbit, the lower jaw 

 being slightly the longer. The maxillary does not qiute extend to 

 below the middle of the pupil. The origin of the dorsal fin corre- 

 sponds to the middle of the distance between operculum and ventrals ; 

 the penultimate dorsal ray is the longest, equal to the length of the 

 head, not quite attaining the base of the anal. The pectoral extends 

 beyond the origin of the dorsal. Dorsal fin with numerous blue spots, 

 and two or three rows of narrow pui'ple spots above them ; upper 

 margin purplish. {Cope.) 

 Michigan. 



6. Thymallus signifer. 



Plewlook-pownlc (JEsqiiim.). Poisson bleu {Cmiacl. Voyagers). 

 Coregonus signii'cr, llichdi-ds. Frankl. Journ. p. 711, pi. 26 (not correct). 



thjmaUoidt's, liichunls. I. c. p. 714 (yoimg). 



Salmo (Thymallus) signifer, Richards. Faun. Bor.-Amer. iii. p. 190, 



pi. 88. 

 Salmo (Thymallus) thymalloides, Richards. I. c. p. 190. 

 Thymalus signifer, Cm. Sj- Val. xxi. p. 450. 



B. 8-9. D. 22-23. A. 12-13. P. 15. V. 9. L. lat. 84. 

 L. transv. 10/1 5. Csec. pyl. 18. 

 The length of the head is nearly one-sixth of the total (without 

 caudal) ; the maxillary extends somewhat beyond the vertical from 

 the front margin of the eye. In mature examples the dorsal rays 

 gradually increase in length from the first to the penultimate, the 

 posterior ones being very long. Dorsal fin blackish, with rows of 

 round blue spots ; trunk with small, subquadrangular, blue spots. 

 Lakes and rivers north of the Mackenzie River. 



13. ARGENTINA. 



Argentina, Artedi, Genera, p. 8 ; Cuv. Regne Anini. 



Argentina et Silus, Gill, Proc. Acad. Nat. Sc. Philad. 1862, p. 15. 



Scales rather large. Cleft of the mouth small ; intermaxiUaries 

 and maxiUaries very short, not extending to below the orbit. Eye 

 large. Jaws without teeth ; an arched series of miniite teeth across 

 the head of the vomer and on the fore part of the palatines ; tongue 

 armed with a series of small curved teeth on each side, except in one 

 species. Dorsal fin short, in advance of the ventrals ; caudal deeply 

 forked. Pseudobranchia3 well developed. Pyloric appendages in 

 moderate numbers. Ova small. 



Marine fish which never enter fresh waters, found in the European 

 seas at considerable depths. 



a. Tongue with teeth. 



1 . Argentina silus. 



GuUax, Vas-sil {Bergen) ; Blankesteen {Sondmor). 



Salmo silus, Ascan. Ic. tab. 24. 



Blankesteen, Strom, Naturkist. Selsk. Skrift. ii. 2. p. 12, tab. 1. fig. 1. 



Coregonus silus, Ctiv. Regne Anim. ; Niks. Prodr. p. 19. 



