518 
ACTJNOrTEHYGII. 
Mioplosus abbreviatus, E. ]). Cope, loc. cit. 1877, p. 814, and 
op. cit. ] 884, p. 88. 
Mioplosus beani, E. D. Cope, loc. cit. 1877, p. 810, and op. dt. 
1884, p. 91, pi. xii. fig. 2. 
Mioplosus lontjus , E. 1). Cope, loc. cit. 1877, p. 815, and op. cit . 
1884, p. 90, pi. xii. fig. 3. 
Mioplosus multiclent atus, E. D Cope, Amer. Nat. vol. xxv. (1891), 
p. 657. — Lower Tertiary (?) ; Bee Hills, South Dakota. 
Mioplosus sauvageanus, E. D. Cope, op. cit. 1884, p. 92. 
Genus PERCA (Artedi), Linnaeus. 
[Syst. Nat. ed. 10, 1758, p. 289.] 
Trunk laterally compressed and elongate-fusiform. Mouth largo 
and protractile, and all teeth very small ; preoporculum with 
serrations, those of lower limb antrorse ; operculum with one spine ; 
seven brauchiostegal rays. Vertebra; 21 in the abdominal, 20 or 
-I in the caudal region. Two dorsal fins, the anterior with 12 to 
10 spines, the posterior with 2 or 3 spines and 12 to 15 articulated 
rays ; anal fin with 2 spines and 8 to 10 articulated rays ; caudal 
fin slightly forked. Scales small and lateral line complete. 
Existing in the fresh waters of the Northern hemisphere, and not 
known to be represented by any extinct species. 
The following specimens are referable to the typical Perea 
fluviatilis, Linn. : — 
P. 8738. Freoperculum described and figured by E. T. Newton, 
Vert. Forest Bed (Mem. Geol. Surv. 1882), p. 120, 
pi. xviii. fig. 1 ; Forest Bed Series (Upper Freshwater 
Bed), West ltunton, Norfolk. Savin Coll. 
P. 8734-35. Maxilla; and scales ; West ltunton. Savin Coll. 
The fishes described as follows are not represented in the Col- 
lection, and their systematic position is uncertain : — 
Perea ( Smerdis ?) lorenti, H. von Meyer, Neues Jahrb. 1845, 
p. 456, and Palaeontogr. vol. i. (1847), p. 105, pi. xii. 
fig. 3. (?) Ichthyolite* , Sir P. Egerton, Quart. Journ. 
Geol. Soc. vol. x. (1854), p. 374, pi. xiii. — Lower Tertiary ; 
Mokattam Hills, Cairo, Egypt. [Imperfect fish ; Mann- 
heim Museum.] 
Perea macracantha, T. C. Winkler, Archiv. Mus. Tcyler, vol. v. 
(1880), p. 94, pi. iii. figs. 7, 8. — Middle Oligocenc; 
