238 Zoological Society : — 



2. That those three species differ by most constant characters from 

 the S. TJmbla and S. Salvelinus of the Continent ; but that S. alpinus 

 of Scotland is closely related to the S. alpinus of Lapland, differing 

 merely by its smaller size when first attaining to maturity, and by 

 the number of vertebrae. 



3. That Iceland is inhabited by a distinct species (5. nivalis). 



4. That the Charrs of Ireland form a separate group by them- 

 selves, distinguished by the feeble development of their dentition ; 

 and that the Charr of Lough Melvin {S. Grayi) is a distinct species 

 from that of Lough Eske and Lough Dan (S. Colii). 



In conclusion, I subjoin a synopsis of the species which I have 

 examined up to the present time, observing, however, that this sy- 

 nopsis is given merely for the purpose of showing afeio of the prin- 

 cipal characters by which the mature individuals of the different 

 species are distinguished : — 



I. Jaws well developed ; teeth of moderate size. 



A. The length of the pectoral fin in the mature fish less than 



one-half of the distance between the roots of the pectoral 

 and ventral fins. 



1, Thirteen dorsal rays. Intermaxillary teeth much 



stronger than those of the maxillary. L.lat. 185. 

 Lower parts silvery. 8. TJmbla. 



2. Fourteen dorsal rays ; intermaxillary and maxillary 



teeth equal in strength. L. lat. 190. Lower 

 parts red. S. Salvelinus. 



B. The length of the pectoral fin in the mature fish more than, 



or equal to, one-half of the distance between the roots 

 of the pectoral and ventral fins. 



1 . The height of the body one-fifth or one-sixth of the 



total length ; the height of the dorsal fin three- 

 fifths or one-half of the length of the head. L. 

 lat. 195-200. S. alpinus. 



2. The height of the body one-fifth of the total length; 



the height of the dorsal fin equals the length of 

 the head without snout. L. lat. 190. The gill- 

 cover not overlapping the root of the pectoral. 

 S. nivalis. 



3. The height of the body one-fifth or one-sixth of the 



total length ; the height of the dorsal fin two- 

 thirds of the length of the head. L. lat. 1/0. 

 The gill-cover overlapping the root of the pec- 

 toral. S. cambricus. 



4. The height of the body one-fourth of the total 



length ; the height of the dorsal fin equals the 

 length of the head without snout. L. lat. 165. 

 The gill-cover not overlapping the root of the 

 pectoral. S. Willughbii. 



