22 EXPLANATION OF PLATE 10. 



6. Front view of bony plates in the Eye of an Iguana. 



7. Profile of the same. 



8. Two of the fourteen component scales of the same. 



I owe these three last figures to the kindness of Mr. Allis 

 of York. 



A 1, 2, 3, 4. Petrified portions of the skin of a small 



Ichthyosaurus, from the Lias of Barrow on Soar, 



Leicestershire, presented to the Oxford Museum, by 



the Rev. Robert Gutch, of Segrave. (Original.) 



In Fig. 1 ; a, b, c, d, are portions of ribs, and e, f, g, h, 



are fragments of sterno-costal bones (nat. size.) 

 The spaces between these bones, are covered with the 

 remains of skin ; the Epidermis being represented by a deli- 

 cate film, and the Rete mucosum by fine threads of white 

 Carbonate of Lime; beneath these the Corium, or true 

 skin, is preserved in the state of dark Carbonate of Lime, 

 charged with black volatile matter, of a bituminous and 

 oily consistence. 



2. Magnified representation of the Epidermis and Rete 

 mucosum. The fine superficial lines represent the 

 minute wrinkles of the Epidermis, and the subjacent 

 larger decussating lines, the vascular net-work of 

 the Rete mucosum. 

 In Fig. 3, the Epidermis exhibits a succession of coarser 

 and more distant folds or wrinkles overlying the 

 mesh-work of the Rete mucosum. 

 In Fig. 4, the Epidermis has perished, and the texture 

 of the fine vessels of the Reta mucosum is exhibited 

 in strong relief, over the black substance of the sub- 

 jacent Corium, in the form of a net-work of white 

 threads.* 



* Nothing certain has hitherto been known respecting the dermal 

 covering of the Ichthyosauri; it might have been conjectured that 

 these reptiles were incased with horny scales, like Lizards, or that 

 their skin was set with; dermal bones, like those on the back of Cro- 



