736 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



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

 widely-separated localities in North America and Europe, that an error 

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

 r^'iferred to as " an exact representation " does not at all corroborate the 

 proportions giv^en in the description, but does approach the proportions 

 lor like measurements in other species of tlie 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 

 snecies, showed the different proportions of 19^ hundredths to 22^. Cal- 

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

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

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

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

 dredths to 25§, 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 dift'erences between Richardson's specimens as 

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



The geographical region froai which the type of T. signifer was 

 obtained, from which the original of the figure and descri]5tion in Fauna 

 Boreali- Americana came, as well as the specimen in the Xational 

 Museum is the valley of the McKenzie Kiver, from whose tributary 

 waters all were taken. 



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

 specimen before me to be a true ThymaUus signifer, notwithstanding the 

 points of difference 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 

 with 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 x>oint 

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



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

 lengtli 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 and 

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

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

 mens. 



