320 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



of this organization consists in the disposition of the straight 

 bony spicula ; an appearance which first attracted my atten- 

 tion when chiselling away the stone, and led to the discovery of 

 some perfect bones, that otherwise would have been destroyed. 

 This structure closely resembles that presented by the liga- 

 mentous fibres of the corium, or skin, and seems to have 

 resulted from an ossified condition of the dermal integument. 

 These scutes vary from half an inch to three or four inches in 

 diameter, and were, probably, disposed in longitudinal series 

 on each side the spine, diminishing in size as they approached 

 the tail. 



Dermal Spines. With the scutes above described there are 

 associated in the specimen before us several flat, thin, angular, 

 osseous plates, from three to seventeen inches in length, (one 

 of these is figured Lign. 67, fig. 4.) The manner in which 

 they are imbedded is shown in Lign. 66. 



The probable nature of these spines was suggested in my 

 original Memoir on the Hylseosaurus, as follows : 



" We have next to direct our attention to the triangular 

 processes which lie on the left of the vertebral column, and 

 three of which are very conspicuous near the base of the left 

 scapula (marked 5, 5, 5, in Lign. 66). Of these bones there 

 are no less than ten, more or less perfect, in different parts of 

 the block ; they vary in size from 5 to 17 inches in length, 

 and from 3 to 7J inches in width at the base. The largest 

 spine is 17 inches long, and 3J wide at six inches from the 

 base, which is 4 inches thick ; it differs somewhat in shape 

 from the corresponding spines, and more nearly resembles one 

 of the displaced bones. The middle process is 13| inches 

 long, and 4-7 inches wide at the base, and is flat, and slightly 

 depressed in the centre : the third is also very flat, and is 1 1 

 inches long. What the nature of these processes may be, it 

 must be confessed is extremely problematical." After stating 

 the objection to their being regarded as processes of verte- 

 brae, or of ribs, it is observed that " another conjecture has 

 occurred to me, and, extravagant as it may seem, appears to 

 be the most probable. It is known that many of the lizards, 

 particularly the Iguanas, have large cartilaginous processes 

 with horny coverings, which form a sort of dermal fringe, or 

 crest, along the back ; in an animal 5 feet long, these spines 

 are about an inch in height. 



