502 
ACTINOPTEKYGII. 
and there is no trace of a gular plate in any specimen examined by 
the present writer. 
One pair of large supratemporal plates occurs behind the occiput, 
and the whole of the trunk is covered with imbricating cycloidal 
scales, which are distinctly invested with gauoine in their exposed 
portion. The vertebral centra are in the form of constricted cylin¬ 
ders, not completely severing the intervertebral portions of the 
notochord ; and they are often strengthened in the later species by 
longitudinal streaks of bone on the periphery. The ribs are robust, 
extending almost or quite to the ventral border ; and some speci¬ 
mens seem to show that they are attached to broad laminar 
parapophyses. The delicate neural arches in the abdominal region 
do not appear to have been fused with the centra, while the right 
and left halves are separate, and the short neural sjnnes are loosely 
apposed to them. Both the neural and haemal arches in the caudal 
region are fused with the vertebral centra and with their respective 
spines ; and where the arch joins the spine there is sometimes a 
slight triangular expansion of the bone. Intermuscular bones are 
observed across the neural arches in the abdominal region. 
The basal bones of the pectoral fin are unknown, but the pelvic 
fin-supports are often well exhibited. Each of the latter is trian¬ 
gular in form, tapering forwards and thickened on the outer border. 
There is nothing worthy of note in the supports of the median fins, 
except that the foremost two or three elements in the dorsal are 
sometimes fused together. , ^ ^ 
X^eptolepis brpttm, Agassiz. 
1830. Cyprinus coryphcenoides, H. G. Broun, Neues Jahrb. p. 14, pi. i. 
fig. 1. 
1832. Leptolepis bronnii, L. Agassiz, ibid. p. 146. 
1833-44. Leptolepis bronnii, L. Agassiz, Poiss. Foss. vol. ii. pt. i. p. 13 ; 
pt. ii. pp. 133, 294. 
1852. Leptolepis constrictus, Sir P. Egerton, Figs. & Descript. Brit. 
Organic Remains, dec. vi. (Mem. Geol. Surv.), no. 9, pi. ix. 
[Nearly complete fishes ; Bath Museum.] 
1858. Leptolepis bronnii, F. A. Quenstedt, Der Jura, p. 238, pi. xxxiii. 
figs. 8-11. 
1874. Leptolepis constrictus, 11. E. Sauvage, Bev. Sci. Nat. vol. ii. 
p. 418, pi. vii. fig. 4, and in Dumortier, Etudes Paleont. Depots 
Jurass. Bassin Phone, pt. iv. p. 29. 
1874. Leptolepis affinis, H. E. Sauvage, ibid. p. 419, pi. vii. figs. 5-9, 
and op. cit. p. 30. [Nearly complete fish.] 
(?) 1874. Leptolepis pronus, H. E. Sauvage, ibid. p. 424, pi. vii. fig. 1 
[Nearly complete fish.] 
(?) 1874. Leptolepis pachystetus, H. E. Sauvage, ibid. p. 426, pi, vii. 
figs. 2, 3. [Nearly complete fish.] 
