90 
ACTINOPTERYGII. 
upper teeth of moderate size, iu a single uniform series ; lower teeth 
in a similar single uniform series, but one pair at the symphysis 
much enlarged. Yertebrae about 50 in number, nearly half being 
caudal; centra with two deep, longitudinally-extended pits on each 
side; ribs comparatively stout, flattened and impressed with a 
longitudinal groove. Pectoral fins rather large ; pelvic fins very 
small; dorsal fin short, opposed to the anal, which is somewhat 
extended; caudal fin deeply forked. Scales large, smooth, and 
very thin. 
The characters of the dentition are here given on the assumption 
that the skull recorded below is rightly referred to this genus. 
Chiromystus mawsoni, Cope. 
1886. Chiromystus maivsoni^ E. D. Cope, loc. cit. p. 4. 
1888, Chiroymjstus maiosoni, A. S. Woodward, Aim. Mag. Nat. Hist. 
[6] vol. ii. p. 134. 
Type. Imperfect trunk; Cope Collection. 
The type species, attaining a length of about 0-4. Depth of 
longest ribs with vertebral centra contained about four and a third 
times in the length from the pectoral arch to the base of the caudal 
fin. Origin of anal fin equidistant from the pelvic and caudal fins. 
Form. Loc. Upper Cretaceous : Bahia, Brazil. 
P. 7345. Imperfect skull, of which the jaws are figured, upside 
down, by Allport, Quart. Journ. Geol. Soc. vol. xvi. (1860), 
pi, xiv. fig. 4. Fresentecl hy Samuel Allport, Esci., 1894. 
P. 7110. Eragmeutary remains of head and anterior part of ab¬ 
dominal region with pectoral fin. 
Fresentecl hy Joseph Maiuson, Esq., 1893. 
P. 5531. Portion of small caudal region, noticed by A. S. Wood¬ 
ward, loc. cit. ; from Itacaranha. 
Presented hy Joseph Mawson, Esq., 1888. 
Genus CHIROCENTRITES, HecJ^. 
[Sitzungsb. k. *Akad. Wiss., math.-naturw. Cl. 1849ypt. i. p. 17.] 
A 
Trunk elongated and laterally compressed ; abdomen trenchant^ 
Teeth ^got compressed to a sharp edge : very irregular in size, and 
at least one pair in the premaxillae much enlarged. About 20 
branchiostegal rays. Vertebrae approximately 60 in number, about 
35 being abdominal; the centra exhibiting two deep, longitudinally- 
extended pits on each side; ribs comparatively stout, each flattened 
