364 CRETACEOUS FISHES. 
Ptychodus Morton, R. 4. (Tab. XXXI. figs. 6&7. Vol. iii. p. 158, Agassiz.) 
The apex of this tooth presents ramifying folds, and its shape and appearance 
differ from all the other species ; the specimen figured in M. Agassiz’s work is 
from the greensand of North America, and from Dr. Mantell’s collection: the 
tooth I have figured appears to me to agree in so many points with that from 
America, that I consider it the same species; it is from Mr. Catt’s collection, 
and was found at Beeding chalk-pit, near Shoreham. 
Ptychodus Owen, new, R. 2. (Tab. XXXI. fig. 2.) 
This is a beautiful species from the upper chalk of Kent. It differs from all 
its congeners in the great irregularity of the surface of the tooth. The folds of 
enamel are rarely parallel to any extent: they generally ramify in various direc- 
tions from two or three principals, winding about, and sometimes bifurcating 
until they disappear at the margin of the tooth ; their continuity is frequently 
interrupted. This species is in the Marquis of Northampton’s collection, in 
Mr. Catt’s and my own; the specimen figured belongs to Mr. Bowerbank, who 
has eight or ten others from one mass. It is a rare, but well-marked species: I 
have named it after my friend Professor Owen. 
The specimens figured (Tab. XXX. figs. 4 & 5) were supposed by M. Agassiz 
to be young and not perfectly formed teeth of this genus. 
Genus Acrodus', Agassiz. 
? to) 
This genus, according to M. Agassiz, presents the nearest affinity with the 
existing Cestracion Philippi, or Port Jackson Shark. 
Acrodus Illingworthi, new, R. 3. (‘Tab. XXX. figs.11 & 12; Tab. XXXII. fig. 9.) 
I have dedicated this species to the Rev. Mr. Illingworth, who discovered the 
fine specimen (fig. 9, Tab. XXXII.) at Southeram chalk-pit. 
It is a long tooth, the centre of which is considerably enlarged and elevated, 
having folds of enamel radiating from the apex ; a well-marked ridge extends 
from the centre to the extremities, from which transverse folds pass off at right 
angles ; the base of the tooth is very large. 
Acrodus cretaceus, new, R. 4. (Tab. XXX. fig. 13.) 
This tooth differs from the preceding in being shorter and broader; small 
We ST sD ON 
akpos summus, ddovs dens. 
