c.r.R 
SILURID^i:. 
329 
Genus RHINEASTES, Cope. 
[Proc. Amer. Phil. Soc. vol. xii. 1872, p. 486.] 
An imperfectly known genus related either to Pimelodus or ^ to 
Arius. Head depressed and bones of cranial roof marked with 
conspicuous rugosity; frontal fontanelle closed, hut marked by a 
smooth deep groove. Teeth minute and villiform, extending over 
vomer. Pectoral fin with robust spine, serrated on one or both 
borders; a nuchal shield between the supraoccipital and the spine 
of the dorsal fin. 
In the typical species, R. peltatus, the nuchal shield is large and 
massive ; in the other Eocene species (forming sub-genus Astephus, 
Cope) it is narrow and short. 
The genus is known only by fragments from the Lower Tertiary 
of North America, and is not represented in the Collection. The 
following species have been named :— 
RJiineastes arcuatus, E. H. Cope, Ann. Pep. U.S. Geol. Surv. 
Territ. 1872 (1873), p. 641, and Yert. Tert. Form. Y^est, 
Book I. (Pep. E.S. Geol. Surv. Territ. vol. iii. 1884), p. 66, 
pi. V. fig. 12. Pimelodus antiquus, J. Leidy, Proc. Acad. 
Nat. Sci. Philad. 1873, p. 99 (name only), and Contrib. 
Extinct Yert. Eauna W. Territ. (Pep. U.S. Geol. Surv. 
Territ. vol. i. 1873), p. 193, pi. xxxii. figs. 44, 45 .— Bridger 
Eocene ; Upper Green Piver, Wyoming. [Pectoral fin- 
spine ; National Museum, Washington.] 
RJiineastes calviis, E. D. Cope, loc. cit. 18/2 (1873), p. 640, and 
op. cit. 1884, p. 65, pi. V. figs. 3-4.—Bridger Eocene; 
Upper Green Piver. [Portion of cranium; National 
Museum, lYashington.] 
RJiineastes pectinatus, E. I). Cope, Bull. U.S. Geol. Surv. Territ. 
vol. i. no. 2 (1874), p. 49, and op. cit. 1884, p. /47, 
pi. V. fig. 13.—Lower Tertiary; South Park, Colorado. 
[Fragment of head and anterior abdominal region; National 
Museum, Washington.] 
RJiineastes peltatus., E. D. Cope, Proc. Amer. Phil. Soc. vol. xii. 
(1872), p. 486, and op. cit. 1884, p. 63, pi. v. figs. 1, 2.- 
Bridger Eocene ; South Bitter Creek, Washakie Basin, 
Yyoming. [Associated head-bones, &c. : National 
Museum, lYashington. The type species.] 
RJiineastes (?) rJiceas., E. H. Cope, Contrib. Canadian Palseont. 
(Geol. Surv. Canada), vol. iii. (1891), p. 3, pi. i. fig* 3* 
Lower Miocene; Cypress Hills, N.W. Territory, Canada. 
[Vertebrse; Canadian Geol. Surv. Museum, Ottawa.] 
