PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 159 

 Measurements — Continued. 



Millimeters. 



Head: 



Distance between outer edges of spiracles 



Greatest width of mouth 



Width of iuterorbital area on the bone 



Length of snout from eye 



Length of eye 



Length of snout from mouth 



Length of si>iracles 



Distance from snout to first dorsal 



Distance between outer humeral spines 



Dorsal : 



Lengtli of base of first dorsal 



Height of first dorsal 



Interval between dorsals 



Len irth of second dorsal 



Height of second dorsal 



Length of bas^^ of vontrals - . 



Distance from snout to end of base of pectoral . 



Distance between outer edges of nostrils 



Distance from snout to outer angle of disk 



Caudal : 



Length of base 



Height 



Ventral : 



Length 



119 

 105 



48 

 153 



30 

 140 



32 

 875 

 125 



32 



24 



16 



30 



26 



134 



510 



90 



463 



21 



7 



* Taken where the ventral insertion ends. 

 AmmoccEtes aureus, n. s. 



1 Petramyzon Fluvialis B.\ch. Franklin's First Jonrney, 1823, p. 705; F. B. A., 

 p. 294. 



? Petromyson horealis Grcl. Pacific R. R. Report, Fishes, p. 377 (without descrip- 

 tion). 



Maxillary tooth single, bicuspid ; maudibulary with seven cusps, those 

 at the ends being larger than the other five. Head shorter than the 

 space occupied by the branchial openings and contained 10^ times in 

 the total length (5^ times in the distance from the end of the lip to the 

 beginning of the first dorsal). The distance from the eye to the first 

 dorsal is 3 times as long as the first dorsal base. Second dorsal base is 

 twice as long as the first, and the fin is twice as high as the first at its 

 highest part. The interspace between the dorsals is about f as long 

 as the head. The distance from the vent to the end of the tail is one- 

 fourth of the total length. Eye nearly twice as large as the largest 

 branchial opening. 



Colors of the alcoholic example : Back plumbeous, sides and belly 

 golden yellow, under surface of head and neck silvery. 



Length of type, 15 inches ; catalogue number, 21524 ; collector's num- 

 ber, 1038, Anvik, Yukon River, Alaska, Lucien M. Turner (Lat. CS^K., 

 Lou. 160'^ W. from Greenwich). Mr. Turner notes that it is extremely 

 abundant and is used for food. 



U. S. National Museum, May 5, 1881. 



