160 
ACTIN OPTEETGII. 
arches were much expanded or that small ossifications 
were developed in the notochordal sheath. 
Purchased , 1848. 
19663-64. A large distorted fish imperfect dorsally, in counterpart 
Boll. Part of the abdominal squamation is displayed. 
Purchased , 1845. 
P. 1595, P. 3525 a. Imperfect head and the lower portion of the 
abdominal region, in counterpart; Boll. 
Egerton <Sf Enniskillen Colls. 
P. 3625 b, C. Two typical specimens showing the feeble character 
of the squamation in the caudal region; Boll. The first 
specimen displays the median fins, and is shown of the 
natural size in PL III. fig. 1. Enniskillen Coll . 
22531. A small fish O065 in length, with remains of all the fins ; 
Boll. Like Ho. 22524, this specimen also appears to 
exhibit pleurocentra and hypocentra in the caudal region. 
Purchased , 1848. 
P. 1596. Small specimen about 005 in length, labelled T. subser- 
ratus by Egerton; Banz, Bavaria. Egerton Coll. 
P. 1593, P. 3626. Two very imperfect small specimens, the second 
wanting the caudal region and the first wanting also the 
head, labelled T. cyclosoma in Egerton’s handwriting and 
evidently to be regarded as the types of that species ; 
from Banz and Ohmden respectively. 
Egerton Enniskillen Colls. 
Tetragonolepis discus, Egerton. 
1853. Tetragonolepis discus, Sir P. Egerton, Quart. J ourn. Geol. Soc. 
vol. ix. p. 278, pi. xi. fig. 5. 
1860. Pleurolepis discus, A. Wagner, Gelehrte Anzeig. k. bay. Akad. 
Wiss. p. 96. 
Type. Head and trunk ; collection of Bev. P. B. Brodie. 
A smaller species than the type, nearly similar in proportions, 
but with a less protuberant abdominal region; the greatest depth 
of that portion of the trunk below the vertebral axis less than three 
times as great as that of the portion above the axis. Scales smooth, 
or with slight rugte following the concentric lines of growth, the 
hinder border not serrated ; those of the abdominal flank relatively 
broad ; ventral ridge-scales very finely serrated. 
Form, Loc. Upper Lias : Gloucestershire. 
