CH^TODONTID^. 
557 
boiirhood of coral reefs. A few genera seem to date back to the 
early part of the Tertiary period, when they ranged further north 
than at the present day. Only two extinct genera, Pygoeus and 
Proantigonia, are provisionally placed here. 
Genus PYG.ffiUS, Agassiz. 
[Poiss. Foss. vol. iv. 1838, p. 16.] 
An imperfectly known extinct genus, with spinous portion both 
of dorsal and anal fin as much extended as articulated portion. 
Dorsal fin continuous and occupying nearly the whole of the back, 
gently rising in front, as gently falling behind; anal fin with 8 or 
9 spines, similar to dorsal but less extended. 
The genus is supposed to be related to the Aphredoderidae by 
Cope (Vert. Tert. Form. West, 1884, p. 85), but no known speci¬ 
men clearly exhibits more than 5 articulated rays in the pelvic 
fins. 
Pygseus coleanuS} Agassiz. 
1838-42. Pygceus coleanus, L. Agassiz, Poiss. Foss. vol. iv. pp. 16 
256, pi. xliv. fig. 5. 
1838-42. Pygceus egertoiti, L. Agassiz, ibid. p. 257. [Imperfect fish ; 
British Museum.] 
1838-42. Pygceus gibhus, L. Agassiz, ibid. p. 257. [Distorted fish j 
British Museum.] 
Type. Imperfect fish ; British Museum. 
A small species about 0'04 in length. Maximum depth of trunk 
somewhat less than its length from pectoral arch to base of caudal 
fin; length of head with opercular apparatus contained twice in 
same length of trunk. Dorsal fin with 14 spines and 15 articu¬ 
lated rays, the latter not longer than the former; anal fin with 
9 spines and 11 articulated rays. 
Form. ^ Log. Upper Eocene: Monte Bolca, near Verona.^ 
P. 551 X, P. 3921. Type specimen in counterpart, exhibiting all the 
' characters mentioned in the specific diagnosis. 
Egerton Ennishillen Colls. 
P. 3923. Smaller well-preserved fish. Ennislcillen Coll. 
P. 1978. Type specimen of so-called Pygceus egertoni, apparently 
differing from the preceding specimens only in its state of 
preservation. Egerton Coll. 
^ An allied species from the Lower Miocene of Chiavon, Vicentin, is de¬ 
scribed by F. Bassani, Atti E. Accad. Sci, Napoli [2] vol. iii. (1889), no. 6, 
p. 90, pi. xiv. figs. 1, 2. 
