SCOPELID^. 
243 
Dermatoptychus macroplitJialmus^ W. von der Marck, Palaeontogr. 
vol. XV. (1868), p. 287, pi. xliii. fig. 4.—Upper Cretaceous; 
Sendenhorst, Westphalia. [Impression of fish, in counter¬ 
part ; Academy of Wiinster. Type species of so-called 
DermatoptycJius.'] ^yu'crt ^ m 
Genus ACROGNATHUS, Agassiz. 
[Poiss. Poss. vol. V. pt. ii. 1844, p. 108.] 
Head with remarkably large orbits and narrow interorbital 
region. Mandibular suspensorium nearly vertical; maxilla ex¬ 
panded behind ; teeth very minute and clustered. Yertebrie 
between 30 and 40 in number. Pectoral fins delicate, inserted 
above the ventral border; pelvic fins comparatively large, with 7 
or 8 very stout rays, inserted far forwards ; dorsal fin short-based, 
in the anterior half of the back, without any excessively elongated 
ray; anal fin very small and remote ; caudal fin forked. Scales 
large, thick, and uniform, not serrated on the hinder border; 
lateral line conspicuous. 
4 4 
Acrognathus boops, Agassiz. 
1844. Acrognathus hoops, L. Agassiz, Poiss. Foss. vol. v. pt. ii. p. 108, 
pi. lx a. figs. 1-4. 
1888. Acrognathus hoops, A. S. Woodward, Proc. Geol. Assoc, vol. x. 
p. 323. 
Type. Imperfect distorted fish ; British Museum. 
The type species, imperfectly known, attaining a length of about 
0*12. Length of head with opercular apparatus considerably 
Exceeding the maximum depth, probably equalling about half the 
length of the trunk from the pectoral arch to the base of the caudal 
fin. Dentary and angular bones of mandible marked with sharp 
radiating grooves. Scales quite smooth. 
Form. Log. Senonian : Sussex and Surrey. 
4304. Type specimen, which has lost the extremity of the tail 
since it was described and figured by Agassiz ; Chalk, 
Lewes. The remarkable stoutness of the pelvic fin s; 
compared with the pectorals is well shown. 
Mantell CoV. 
49775. Portion of mandible and anterior vertebrse; Upper Chalk, 
Shalford, near Guildford. Capron Coll. 
r2 
