370 CRETACEOUS FISHES. 
mensions and coarser structure of the head-bones, for which I propose the name 
of Microdon occipitalis: Mr. Catt has also some teeth considerably larger than 
the two former, which indicate a third species (Tab. XXXII*. fig. 5). 
Genus Gyrodus', Agassiz. 
Gyrodus cretaceus, R. 3. (Tab. XXX. fig. 15. Vol. ii. part 2. pp. 233 & 246, 
Agassiz.) 
The specimen from Dr. Mantell’s collection, to which M. Agassiz has 
applied this name, is very much smaller than the one figured in this work ; but 
as the latter resembles it closely, and was found at the same pit, near Lewes, I 
cannot but consider it a larger and more perfect example of the same species. 
From Mr. Bowerbank’s cabinet. 
Gyrodus angustus, R.1. (Tab. XXX. fig. 14; and Tab. XXXII. fig. 1. 
Vol. ii. part 2. pp. 235 & 246, Agassiz.) 
M. Agassiz originally named this species from a few teeth found at Houghton ; 
since then I have had the good fortune to find the magnificent and instructive 
figured specimen, which displays the two lower jaws and a great portion of 
the body with the scales. The structure of the teeth is described in Professor 
Owen’s ‘ Odontography,’ page 72 ; the larger teeth are smooth, and very much 
resemble a cucumber-seed ; the smaller ones have a circular depression ; the 
scales when first relieved from the chalk had a beautiful lustre ; they are pitted, 
and have long processes which overlap each ether. The scales along the nape 
of the neck terminate upwards in a row of projecting points, giving a highly 
ornamental finish to the outline of the fish. 
Gyrodus conicus, new, R. 4. (Tab. XXXII. fig. 8.) 
The conical character of these teeth sufficiently distinguishes them from those 
of G. cretaceus, and warrants a new specific name. The specimen is from Mr. 
Bass’s collection at Brighton, and found at Malling. 
' yupos gyrus, ddovs dens. 
