154 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



Mr. Morris ; the frontispiece of that volume represents a fine 

 carapace in the Norwich Museum. 1 



Mr. Woodward states that the buckler or shell of this 

 Chelonian reptile often forms the nuclei of the septaria or 

 cement-stones which occur in the eocene clay of the Norfolk 

 coast ; the one figured was dredged up from the Stour Ridge, 

 Avhich lies four miles out at sea from Harwich Harbour ; it is 

 22 inches long and 18 wide. Specimens of the convex or 

 outer surface of the carapace are less common than those that 

 expose the interior. 



This Turtle was figured and described by Mr. Konig, under 

 the name of Testudo plana in the I cones Sectiles, fig. 192 ; 

 and Prof. Owen has figured the Museum specimen (which is 

 13| inches long, and 10 inches wide), in his " Monograph on 

 the Fossil Reptilia of the London Clay," PL XL and XII. , 

 as Chelone crassicostata ; a name derived from the great 

 thickness of the ribs which is peculiar to this species ; but it 

 appears to me improper to expunge the specific name of 

 a fossil that has been figured and described by an original 

 observer, with sufficient clearness to enable the species to be 

 identified. In every department of natural history unneces- 

 sary changes in nomenclature are most serious impediments 

 to the advancement of scientific knowledge. 



CHELONIA Breviceps. ("Pictorial Atlas," PI. LXIX. fig. 

 2, 3.) A nearly perfect cranium of a marine turtle from the 

 Isle of Sheppey, named Emys Parkinsonii by Mr. Gray, and 

 Chelone breviceps (short-skull) by Professor Owen, is placed 

 jn this Case : it approaches in form the recent C. my das. 

 In Mr. Bowerbank's collection there is a cranium of the same 

 species, attached to the carapace and plastron: it is a small 

 turtle, about seven and a half inches long. 2 



In the late Mr. Dixon's collection (now added to the Na- 

 tional Museum) there were several species of eocene turtles, 

 which are figured and described in his work ; as, for example, 

 C. declivis, C. trigoniceps, &c. ; but these interesting fossils 

 are not at present exposed to view. 



FOSSIL TURTLES OP THE WEALDEN. Wall-case A. B. 



1 " Synoptical Table of British Organic Kemains;" by Samuel Wood- 

 ward: Norwich, 1830. 



2 Figured in " Palaeontographical Monograph," 1849, PI. I. II. 



