Greensand Fishes 65 



coprolite band of the county are the palatal teeth of various 

 species of pycnodont fishes, all of which are characterized by 

 their crushing type of dentition. Remains of these fishes have 

 been described in two papers contributed to the Geological 

 Magazine 1 by Dr A. Smith Woodward. The first genus, 

 Atkrodon, of which there are two species, A. crassus and A. 

 jessoni, from the formation under consideration, is known only 

 by the teeth of the splenial element of the lower jaw. These 

 indicate fishes allied to the Jurassic Mesodon, but are more 

 irregularly arranged, with the median longitudinal series less 

 well differentiated. The genus Coelodus, in which the teeth 

 on the vomer of the palate are arranged in five longitudinal 

 series, while those of the splenial of the lower jaw are elongated 

 transversely and form three rows, is likewise represented by 

 two species peculiar to the Cambridge Greensand. Of these 

 C. inaequidens is comparatively common, but C. cantabri- 

 giensis is at present known only by a single splenial bone, 

 with its teeth, in the collection of the British Museum. The 

 third genus is the imperfectly known Anomoeodus, of which 

 the vomer is nearly flat (instead of convex), and carries teeth 

 of irregular sizes in from three to five longitudinal series, 

 while the splenial dentition is restricted to a small area of the 

 bone, and consists of one large series of teeth, flanked on the 

 inner side by at least one row of smaller teeth, and externally 

 by two or more similar rows. The Cambridge species comprise 

 the large A. superbus, the medium-sized A. confertus, and the 

 diminutive A. carteri. Another type of enamel-scaled, or 

 ganoid fish, the well-known Lepidotus, of the family Semi- 

 onotidae, is apparently indicated by certain scales from the 

 Cambridge Greensand in the collection of the British Museum 2 . 

 Another specimen in the same collection indicates a species of 

 the genus LopMostomus peculiar to the Cambridge Greensand, 

 namely L. affinis ; the genus belonging to the family Eugna- 

 thldae. 



Passing on to fishes of a more modem type, we have 



1 Decade iii. x. 493 (1893), and dec. iv. u. 207 (1895). 



2 Woodward, op. cit. (4) n. 207. 



M. & S. 5 



