Squamation . — The scales are best exhibited in the type-specimen (PL 
V, Pig. 2), wliich shows two very deep series upon the middle of the anterior 
portion of the flank, the vertical measurement of the deepest l)eing a little 
more than three times their antero- posterior dimension. Above and below 
there is also another remarkably deep series ; and the only scales as broad as 
deep are those upon the dorsal and ventral aspects of the abdomen, and upon 
the caudal pedicle behind the dorsal and anal fins. The dorsal and ventral 
ridge-scales are conspicuous. 
I\e7nark's . — This species is distinguished by the depth of the trunk, 
Ihc small size of the head, and the relative length of the dorsal fin. 
PllISTISOMUS CRASSUS, Sp. 7100. 
PI. V, Pigs. 5-7. 
Ohs . — The principal characters of a very robust species with large ■ 
scales are illustrated by the following specimens : — 
(c) Type-specimen, wanting the dorsal fin and the u})per lobe of the 
fail, shown of the natural size in PI. V, Pig. 5. 
{}}) Head and incomplete trunk, partly shown of the natural size 
in PI. V, Pig. 6. 
(c) Trunk, wanting the head and paired fins, the caudal region 
being shoAvn of the natural size in PI. V, Pig. 7. 
((/) Imperfect fish, showing squamation. 
(e) Imperfect large fish. 
General Foinn. — Compared with the typical species, the trunk is 
elongated and robust, the greatest depth being contained about three times 
in the total length. The head is large, and the distance between the extremity 
of the snout and the jiosterior margin of the ojierculum is at least one 
quarter of the total length. The dorsal fin is much elevated, being as high 
as long ; and the caudal fin is large. 
Head and Opei'cidar Apparatus. — The head in the original of PI. V, 
Pig. 0, exhibits a few points of interest, and suggests that there was a certain 
amount of ossification in the chondrocranium, as in Hapedius. IVIcmbrane- 
l)ones are also well developed, the roof l)eing protected with thick plates, and 
a slender bone, like the parasphenoid, lying across the orbit. The mouth is 
small, with closely arranged styliform teeth, two l)eing comprised within the 
