mu.schi;l-kalk, lias, and oolite. 
281 
Fishes of the Muschelkalk, Lias, and Oolite 
Formations. 
The Fishes of the Muschelkalk are either 
peculiar to it, or similar to those of the Lias and 
Oolite. The fi gure engraved at PI. 27% is 
selected as an example of the character of a 
family of Fishes most abundant in the Jurassic 
or Oolite iormp.tion ; it represents the genus 
Oyrodus in the family of Pycnodonts, or thick- 
toothed Fish es, which prevailed extensive! y during 
the middle ages of Geological History. Of this 
extinct family there are five genera. Their leading 
character consists in a peculiar armature of all 
parts of the mouth with a pavement of thick 
round and flat teeth, the remains of which, under 
the name of Bufonites, occur most abundantly 
throughout the Oolite formation.* The use of 
this peculiar apparatus was to crush small shells, 
and small Crustacea, and to comminute putres- 
cent sea-weeds. The habits of the family of 
Pycnodonts appear to have been omnivorous, 
‘•ind their power of progression slow.f 
* PI. 27'. Fig. 3. represents a five-fold series of these teeth on 
•■he palate ofPycnodus trigonus from Stonesfield; and Fig. 2, a 
senes of similar teeth placed on the vomer in the palate of the 
t^yrodus Umbilicus from the great Oolite of Durrheim, in Baden. 
t A similar apparatus occurs in a living family of the Order 
^'ydoids, in the case of the modern omnivorous Sea Wolf, Anar- 
