1879. | A Contribution to the Zoblogy of Montana. 441 
I may here mention that the Hydorhynchus siderius Cope, is a 
fybognathus ; its enumeration under the former head being the 
result of some one’s inadvertence. The Rhinichthys maxillosus 
of that report I believe now to be distinct from the species I © 
called by that name, and I propose that it be termed R. /rans- 
montanus. It differs from the more eastern species in having the 
dorsal fin equidistant between the base of the caudal and the end 
of the muzzle, and in having the longitudinal series of scales 
below the lateral line more numerous (12-13) and equal to the 
number of scales above it. In R. maxillosus, from Battle creek, 
they number 19-72, 
Lsospondyli. volo tergisus Les. —Juaith river and pools of 
the Missouri near Battle creek. 
Coregonus villiamsonit Gird—Heads of the tributaries of the 
Upper Missouri. 
Ginglymodi.—Lepidosteus productus Cope, and L. otarius Cope.— 
I found both these species in pools left by the Missouri river near 
to Battle creek, maintaining their characters exactly. They differ 
in both proportions and color. The L. productus is lead colored 
above and white below, the colors gradually commingling on the 
sides. There are no spots on the sides nor at the base of the 
tail, and there are three spots on the caudal fin. In Z. otarius of 
the same small size, the darker lead color of the back is abruptly 
separated from the white of the belly by a row of dark spots, 
and there is a black spot at the base of the caudal fin. The spots 
on the latter are large and more numerous. 
The specimens I obtained of both species are young. One of 
the Z. productus, of eight and one-half inches in length, exhibits 
the persistent caudal chorda dorsalis with dermal margin, which 
has been observed by Prof. Wilder. It is nearly absorbed in a 
rather larger example. 
Chrondrostei.— Scaphirhynchops platyrhynchus Raf—Abundant 
in the Missouri. An individual taken at Fort Benton weighed 
forty-seven pounds. I secured its head. 
1 Proceed. Academy, Philadelphia, 1865, p. 86. 
