PACHYCOKMIDJE. 
399 
of the caudal fin the expanded supporting haemal spine 
is conspicuous, and there is a slight longitudinal ridge on 
this bone where the rays of the upper and lower lobes 
diverge. A few uniserial fulcra are intercalated between 
the tips of the gradually lengthening rays on the anterior 
borders of the fin. All the scales preserved both behind 
the pectoral arch and at the origin of the caudaJ fin are 
ornamented with very fine tubercles. Leeds Coll. 
P. 6920. Expanded haemal arch from base of caudal fin either of 
this or the preceding species; near Peterborough. 
Leeds Coll. 
The following specimens are not specifically determined:— 
42368 a, 43028 a, P. 347 a. Five fragments of jaws of a small 
species, noticed in Geol. Mag. [3] vol. vi. 1889, p. 451; 
Kimmeridge Clay, Weymouth. 
Purchased , 1870, 1871, 1881. 
P. 6918. Two very stout left maxillae, more or less imperfect; 
Oxford Clay, near Peterborough. Leeds Coll. 
36308. Expanded haemal arch from base of caudal fin, associated 
with fragments of rays ; Oxford Clay, Christian Malford, 
Wiltshire. Purchased, 1861. 
Genus PROTOSPHYRiENA, Leidy. 
[Trans. Amer. Phil. Soc. vol. xi. 1857, p. 95.] 
Syn. Erisichthe, E. D. Cope, Proc. Acad. Nat. Sci. Philad. 1872, 
p. 280. 
Pelecopterus, E. D. Cope, Vert. Cret. Form. West. (Rep. U.S. 
Geol. Surv. Territ. vol. ii. 1875), p. 244 c. 
An imperfectly definable genus known only by the head, pectoral 
arch, and pectoral fins, which are closely similar to the corresponding 
parts of Hypsocormus. Rostrum ordinarily much produced ; pre¬ 
maxilla large and triangular in shape. Dentition powerful, all the 
principal teeth much compressed, with sharp anterior and posterior 
edges, and fixed in deep, complete sockets; those of the vomer, 
premaxilla, and splenial especially large, and similar teeth pro¬ 
jecting forwards from the downwardly-curved anterior extremity 
of the oral border of the dentary ; those of the maxilla and hinder 
portion of dentary comparatively small and in a single close series; 
