366 CRETACEOUS FISHES. 
Genus dAulodus', new, Agassiz. 
Aulodus Agassizi, R. 4. (Tab. XXXII. fig. 6.) 
This genus is nearly allied to Strophodus and Psammodus. The name Aulodus 
was proposed by M. Agassiz. The figured specimen from Mr. Catt’s cabinet is 
the only example I have seen. It is a very thick, strong tooth, with large and 
distinct calcigerous tubes ; the grinding surface is much worn and smooth. 
Genus Plethodus®, new, Dixon. 
The name Plethodus is proposed for this genus, in reference to the multitude 
of calcigerous tubes of which the tooth is composed. 
Plethodus expansus, R.4. (Tab. XXXIII. fig. 2.) 
This imperfect tooth from Mr. Catt’s cabinet, of which the engraving is a good 
representation, is smooth and flat ; it is not quite half an inch in thickness. It 
is a much-worn mass of calcigerous tubes, which in a horizontal section under 
the microscope have nearly the same arrangement as in Ptychodus and Psam- 
modus. I have seen two or three other specimens not more than a quarter of an 
inch in thickness, showing the under surface to be concave and smooth as in 
Cochliodus®. 
Plethodus oblongus, R. 3. (Tab. XXXII*. fig. 4.) 
In Mr. Coombe’s and Mr. Catt’s cabinets there are specimens of a tooth 
apparently belonging to this genus, but differing from those of the preceding 
species in their small size and oblong contour ; they measure one inch in length 
by half an inch in breadth at the widest part; the surface is pitted or marked 
with small depressions varying in size and depth. The calcigerous tubes are 
very distinct. 
Family SquaLip2&. 
Genus Corax*, Agassiz. 
Corax maximus, new, R.2. (Tab. XXX. fig. 17.) 
A strong, thick tooth, from the upper chalk, much larger than C. falcatus, 
’ aidos fistula, déovs dens. 2 Anos multitudo, ddovs dens. 
° A Cestraciont genus named by M. Agassiz from the mountain limestone. 
* képaé corvus. 
