PTCXODONTlDiE. 
275 
fossil is extremely distorted by crushing; while the two specimens 
compared as regards the dentition, exhibiting only the series in 
side-view, do not display homologous teeth. 
P. 65. Obscurely preserved and distorted fish in hard limestone, 
described and figured, loc. cit.; Hakel. The amount 
and direction of distortion are indicated by the dis¬ 
placement of the lobes of the tail. Lewis Coll. 
Palseobalistum fiabellatum (Cope). 
1886. PycnodusJlcibellatus, E. D. Cope, Proc. Artier. Phil. Soc. vol. xxiii. 
p. 6. 
1890. Palceobalistum Jlabellatum, A. S. Woodward, Geol. .Mag. [3] 
vol. vii. p. 394. 
Type. Imperfect fish ; Cope Collection, Philadelphia. 
A species attaining a length of about 0*2, differing from other 
forms (according to Cope’s description) in its relatively short anal 
fin. Dorsal fin comprising 53, anal fin only 24 rays. 
The neural spines are shown to be united by interdigitations of 
their laminar expansions, as described above in P. goedeli. The 
circumstance that only four basal bones are recognizable in the 
pectoral fin, is probably due to imperfection in preservation ; there 
being distinctly not less than seven in P. goedeli (no. 39232). 
Form. Sf Loc. Cretaceous : Province of Sergipe del Rey, Brazil. 
Hot represented in the Collection. 
Fragments apparently of a species of Palceobalistum from the 
Cretaceous of Comen, Istria, are also described by B. Emer, 
Sitzungsb. k. Akad. Wiss., math.-naturw. Cl. vol. lvi. pt. i. (1867), 
p. 183. 
Genus PYCNODUS, Agassiz. 
[Poiss. Boss. vol. i. 1833, pi. G. fig. 1 (name and fig. only), vol. ii. 
pt. i. 1833, p. 16, and pt. ii. 1844, p. 183.] 
Syn. Periodus , L. Agassiz, ibid. vol. ii. pt. ii. 1844, p. 201. 
Trunk deeply fusiform, gradually passing into a slender caudal 
pedicle. Head- and opercular bones externally rugose and punc¬ 
tate ; teeth smooth, or with a slight apical pit and feeble rugosity; 
oral surface of vomer slightly convex from side to side, with teeth 
in five longitudinal series; splenial dentition comprising three 
series of teeth, the innermost the largest. Xeural and haemal 
arches of the axial skeleton of trunk expanding to encircle the 
notochord. Pin-rays delicate, spaced, articulated and somewhat 
x 2 
