MILNER ON THE GRAYLING. 737 



The length of the maxillary is greater iu the southern forms, and the 

 distances from snout to dorsal and anal tins are greater. 



The northern specimens differ from T. tricolor iu having a maxillary 

 of less length and less distance from the snout to the insertions of the 

 dorsal and the ventrals, and smaller diameter of orbit. Teeth are pres- 

 ent on the tongue. 



Specimens of the Montana grayling, sent from tributaries of the Mis- 

 souri by George Scott Oldmixon, acting assistant surgeon U. S. A., and 

 by Professor Hayden, to the National Museum collection, have greater 

 height of body than in the Michigan species. Of the latter, out of seven 

 specimens measured, the maximum height was 22J hundredths of the 

 length, the minimum being .20 ; the mean height was .21 Out of six 

 good specimens of the former, the maximum was .24|of the length, and 

 the minimum was .23^, which was more than the greatest height found 

 iu the eastern specimens. This character was confirmed iu the evident 

 slenderness of all the individuals in a collection of seventy-five speci- 

 mens from Ausable Eiver, Michigan. 



A comparison of measurements of least height of tail also evinced 

 similar differences. The maximum in the six Montana specimens was 

 9 hnndredths of the length, and the minimum was .08 J; the average 

 being .OSf. The average in the seven Ausable specimens was .07^ ; the 

 maximum being .08^, and the minimum only .07. 



The width of the head aflbrds another character of similar import. 

 In six specimens examined, the width of the head is much greater than 

 in any of the specimens from Michigan. The maximum shown by the 

 callipers was .48^ of the length of the head, and the minimum .45^ ; 

 while out of seven Michigan specimens, the greatest was .44^, and the 

 least .41|. The width of the interorbital areas corresponded with the 

 differences of the thickness of the head. 



The maximum and average lengths of the maxillary and the mandi- 

 ble, and also of the distance from tip of snout to orbit, are greater in 

 the Michigan species ; though individuals from each locality were found 

 iu which they formed an equal j)roportion of the length of the head. 



The diameter of orbit is greater in the Michigan fish. The maximum 

 in seven fishes is .31^ of the length of the head, while the minimum is 

 .28|. In six Montana specimens, the maximum is .28^, and the minimum 

 is .24. 



In twenty-five or thirty specimens of the Michigan species examined, 

 no matured specimen was found that had the least vestige of a tooth 

 upon the tongue. Three young individuals out of seven or eight were 

 found to have teeth in this position, from one to three very minute ones 

 being found present. 



Out of nine specimens from Montana, partly grown and matured, 

 every one had a distinct patch of teeth upon the tongue, from seven to 

 ten in number. 



The length of the head from snout to edge of opercle, and from snout 

 S. Mis. 74 47 



