1863.] DR. A. GUNTHER ON THE BRITISH CHARRS. 9 



that I have misunderstood a part of the description of the former, 

 and that the latter has given his notes from young specimens. "When 

 Linnseus says that the head of his specimen ( 1 2 inches long) was 

 1^ inch, he measured only the top of the head from the end of the 

 snout to the occiput ; whilst ichthyologists of the present time take 

 the lateral length of the head from the end of the snout to the gill- 

 opening. Nilsson says that S. alpinus has shorter pectoral fins than 

 S. salvelinus ; this is correct if we examine specimens of the former 

 only 8-10 inches long, but in a mature state S. alpinus has the 

 longer pectorals. Therefore the characters by which I have formerly 

 distinguished the S. alfinus from S. willughbii and S. cambricus 

 cannot be retained, whilst others, affording easy specific distinctions, 

 become evident on comparison of actual specimens. The two Bri- 

 tish species mentioned have a less number of transverse series of 

 scales ; S. willughbii, besides, has the body more elevated, whilst S. 

 cambricus has a longer head, and the base of the pectoral overlapped 

 by the gill-cover apparatus. The Iceland Charr, again, differs from 

 8. alpinus in its elevated dorsal fin. 



I have mentioned above that I refer to this species a number of 

 specimens from Lapland, Scotland, and from the Orkneys. After 

 having hesitated for a long time, I prefer doing so, as they certainly 

 are more closely allied to one another than to any of the other forms. 

 Future observations on a more perfect series than that which I 

 have at present, and especially an examination of a greater number 

 of immature and of very old specimens, will settle this point. The 

 specimens from Scotland and Lapland appear to agree in almost every 

 point of importance, but in the number of vertebrae and in the size : 

 whilst the Lap Charr does not attain to maturity before it has at- 

 tained to a length of 12-13 inches, the Scotch individuals are mature 

 at a size of 9 inches. The specimens from the Orkney Islands are 

 6 inches long, and apparently correspond in age to a Lap specimen 

 of 10 inches in length. The immature state of S. alpinus of both 

 countries is distinguished by short pectoral fins ; but, whilst those 

 fins have attained to their full relative length in Scotch specimens of 

 9 inches in length, the Lap specimens are 13 inches long at the same 

 period. Other differences may be observed on comparing these 

 young Charrs, especially in the form of the head, which is consider- 

 ably less elongate in the Scotch individuals ; but in order to ascer- 

 tain whether this character is constant, it would be necessary to com- 

 pare a greater number of specimens than I have at present. 



I shall first describe one of the mature specimens sent by Mr. 

 Wheelwright from Quickjock. 

 '■ Description of a male specimen, length 13 inches 8 lines. — Head 

 and body compressed, but slightly elevated ; its greatest depth is 

 below the origin of the dorsal fin, where it is one-fifth of the total 

 length (to the end of the middle caudal rays). The least depth of 

 the tail is rather less than the length of the base of the dorsal fin. 

 The height of the head above the mandibulary joint equals the dis- 

 tance between the posterior margin of the orbit and the end of the 

 operculum. The top of the profile of the head is somewhat elevated 



