86 
ACTIXOPTEETGII. 
Genus NOTOPTERUS, Lacepede. 
[Hist. Nat. Poiss. vol. ii. 1800, p. 189.] 
Trunk fusiform, with very short abdominal region and much 
elongated and attenuated caudal region. Dorsal fin very small, in 
the caudal region; anal fin much extended and confluent with the 
rudimentary caudal fin. A double series of short ventral ridge- 
scales in the abdominal region. 
Notopterus prim2evus, Giinther. 
1876. Kotoptems 2 ^rimcBvi(s, A. Giinther, Geol. Mag. [2] vol. iii. p. 439^ 
pi. xix. 
Type. Imperfect fish ; British Museum. 
An imperfectly known species, about 0*3 in length. Lower part 
of preoperculum and some ridges of mandible serrated. About 13 
abdominal vertebrae. Dorsal fin above 14th and 15th caudal 
vertebrae. Scales very small. 
Form. Log. Freshwater Tertiary Lignite : Padang, Sumatra. 
47512. Type specimen described and figured by Gunther, loc. cit. 
Presented hy Herr JR. D. M. Yerheeh, 1876. 
Family CHIROCENTHID.H. 
Supraoccipital bone prominent, partly or complete^ separating 
the parietals in the median line; squamosals reduced, and otic 
region very prominent ; parasphenoid enclosing a basicranial canal > 
snout not produced; cheek-plates well developed. Mandibular 
suspensorium inclined forwards, but gape of mouth wide and more 
or less directed upwards ; premaxilla and maxilla robust and firmly 
fixed, both entering the upper border of the mouth ; teeth acuminate, 
almost or exclusively confined to the premaxilla, maxilla, and dentary 
bones. Opercular apparatus complete, with branchiostegal rays, but 
no gular plate. Vertebral centra well ossified, none with transverse 
processes ; ribs nearly or completely encircling the abdominal cavity ; 
hsemal arches more or less fused at the base of the tail. Inter¬ 
muscular bones present. Fin-fulcra absent; fin-rays divided and 
closely articulated distally ; post-temporal bones in contact with 
postero-lateral angles of cranium; dorsal and anal fins remote. 
Scales thin and cycloid. In the recent genus :—Vo pseudobranchiae 
air-bladder incompletely divided into cells ; no pyloric appendages ^ 
intestine short, with a rudimentary spiral valve. 
