66 Vertebrate Palaeontology of Cambridgeshire 



the problematical Plethodus expansus of the Sussex Chalk 

 represented by lower dental plates in the formation under 

 consideration. The lancet-like teeth of Protosphyraena /</<>.>-, 

 already alluded to when discussing the fishes of the Chalk of 

 the county, are exceedingly abundant in the coprolite beds, as 

 are also the conical beaks of the same fishes. Four other 

 species of the same genus, namely P. brevirostris, P. depressa, 

 P. keepingi, and P. ornata, have been established on specimens 

 of the last-named element of the skeleton from the Cambridge 

 Greensand. 



The Gault of the county appears to be practically devoid 

 of vertebrate remains, the only specimen of that nature with 

 which the writer is acquainted being the arm-bone, or 

 humerus, of a turtle from the Barnwell pits, preserved in 

 the Sedgwick Museum 1 . 



The coprolite beds of the Lower Greensand of Wicken, 

 Cambridgeshire, have yielded a large number of water-worn 

 bones and teeth of reptiles and fishes similar to those from 

 the corresponding formation of Potton, in Bedfordshire. 

 Most if not all of these remains have been derived from 

 the denudation of preexisting formations. A large series 

 of them is preserved in the Sedgwick Museum. Among 

 the more common of these remains are bones and teeth of 

 Ichthyosaurus and of the great short-headed sauropterygians 

 of the Kimeridge Clay known as Pliosaurus ; some of the 

 Wicken vertebrae having been named by Prof. Seeley, with- 

 out description, P. microdirus. As derivatives from the 

 latter formation may also be reckoned the teeth of the 

 giant crocodilian Dacosaurm ; while the teeth and bones of 

 lyuanodon (the great bipedal herbivorous dinosaur) have 

 been washed out from strata of Wealden age. The scales 

 and button-like teeth of the large Kimeridgian species of 

 the enamel-scaled fish Lepidotus are also met with at Wicken, 

 as are likewise the palatal and splenial dental plates of various 

 pycnodont fishes. The teeth and bones from the Wicken 

 deposits, like those from Potton, are stained red by the 

 1 Seeley, "Index to Ornithosauria, etc." 73. 



