A. Smith Woodward — Oreensand Ganoid Fishes. 207 



III. — A Synopsis of the Remains of Ganoid Fishes from the 

 Cambridge Greensand. 



By Arthur Smith Woodward, F.L.S., F.G.S., 

 Of the British Museum (Natural History) . 



(PLATE VIII.) 



THE remains of fishes discovered in the Cambridge Greensand are 

 all very fragmentary, and have not hitherto been subjected to 

 the detailed comparison with other Cretaceous Ichthyolites which 

 their interesting stratigraphical position renders desirable. Many 

 specimens, however, are capable of at least generic determination, 

 while many others are sufficiently characteristic fragments for the 

 definition of the species. The present writer has thus been much 

 interested during the past few years in studying collections of these 

 fossils, and the following notes embody some of the results in 

 reference to the ganoid fishes. The British Museum (Natural History) 

 having recently acquired the collection made from the Cambridge 

 Greensand by Mr. Thomas Jesson, F.G.S., nearly all the known 

 species are now represented here ; but the writer has also availed 

 himself of the privilege of making use of the fine series in the 

 Woodwardian Museum, Cambridge, and the Philosophical Society's 

 Museum, York, thanks to the kindness of Professor McKenny Hughes, 

 Mr. Henry Woods, and Mr. H. M. Platnauer. Mr. James Carter, 

 M.R.C.S., has also kindly lent some Pycnodont jaws from his private 

 collection. 



Genus Lepidotus, Agassiz (?). 



A few scales identical in form with those of the genus Lepidotus, 

 showing the produced angles of tlie overlapped portion, are con- 

 tained in the Jesson Collection (Brit. Mus. No. P. 7232). The 

 lai'gest measures about 003 m. in the depth of its exposed area. 

 They all seem to have been smooth, but a small boring organism has 

 destroyed much of the surface. 



Family PYCNODONTID^. 

 Genus Athrodon, Sauvage. 



The genus Athrodon has already been recorded from the Cam- 

 bridge Greensand on the evidence of an abraded splenial bone ; and 

 there is some reason for also assigning to it a vomer with seven 

 irregular longitudinal series of teeth, in the Woodwardian Museum.^ 

 A second species is now indicated by another splenial in Mr. Jesson's 

 collection, and this appears to be distinct from all forms hitherto 

 described. 



1. Athrodon crassiis, A. S. Woodward, Geol. Mag. Dec. Ill, Vol. X, 

 (1893), p. 435, PL XVI, Fig. 3. 



Type. Eight splenial : Woodwardian Museum, Cambridge. 

 1 A. S. Woodward, Geol. Mag. [3] Vol. X (1893), p. 435, PI. XVI, Fig. 4. 



