736 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



pared with a large number of specimens of four species from sevoii 

 widely-separated localities ia ]S"ort!i America aud Europe, that au error 

 is naturally supposed. To support this suspicion, the figure which is 

 r.'ferred to as " an exact representation " does not at all corroborate the 

 proportions given in the description, but does approach the proportions 

 for like measurements in other species of the genus. 



To illustrate this statement, the length of the head compared to the 

 length of the fish, excluding the caudal in twenty individuals of different 

 species, showed the different proportions of 19J hundredths to 22.J. Cal- 

 cidated from the measurements given in Richardson's description, the 

 length of head is only 15J hundredths, while in the figure it is found 

 to be 17. The distance from snout to edge of orbit, compared to the 

 length of head in seventeen specimens, had a range of from 22 hun- 

 dredths to 258, while in the description it is 14^ hundredths, and in the 

 drawing 26. 



It has seemed to me that these discrepancies invalidate to a great 

 extent the value of the differences between Richardson's specimens as 

 described in his later work and the specimen from Fort Simpson. 



The geographical region from which the type of T. signi/er was 

 obtained, from which the original of the figure and description in Fauna 

 Boreali- Americana came, as well as the specimen in the i!^ational 

 Museum is the valley of the McKeuzie River, from whose tributary 

 waters all were taken. 



After consideration of these fticts, I have decided to determine the 

 specimen before me to be a true Thyniallus sUjnifer^ notwithstanding the 

 l)oints of ditterence from Richardson's description, before referred to, in 

 the number of scales in the lateral line, and the presence or absence of 

 teeth upon the tongue. 



Three specimens are in the collection from the Yukon River of Alaska, 

 which arrived in too bad condition to be of value. The heads afford 

 some characters for comparison, and, in all particulars, correspond well 

 witli T. signifer. 



The width of the head and of the operculum in two specimens of a 

 grayling from Alaska — skins — labeled "St. Michael's, Norton Sound, 

 H. M. Bannister" — but which, it is believed, were brought to that point 

 from some stream at a distance — does not resemble T. signifer. 



These have greater width in the iuterorbital area, and a much greater 

 length in the operculum than in the other specimens from the far north 

 as well as south; the proportions of these measurements to the length 

 of the head exceeding the maximum in all of the other graylings exam- 

 ined, except in the first-mentioned character in one specimen of the 

 Michigan species. In other particulars they correspond. 



The bones of the head in the northern specimens are heavier aud 

 more compact. A foramen situated in the frontal suture in the gray- 

 lings from Michigan aud Montana was not found in the northern speci- 

 mens. 



