154 PHILOSOPHICAL TRANSACTIONS. [aNNO J786 



the question. Dr. Gray was so kind as to go with me to the lower apartments 

 of the British Museum, where we found, though not without difficulty, the 

 skeleton much neglected, spoiled, and deprived of several interesting parts. I 

 admired however the remains of it, being infinitely pleased with the transverse 

 sutures, fig. 1 , 2 abcf^i^, by which not only those of the neck and thorax, but 

 those of the loins also, are divided, and which I made a drawing of, as large as 

 the life, the 20th of October, 1785, of which fig. i and 2 are very accurate 

 copies. 



I confess I had not observed that particular division or suture in the skeleton 

 of a small crocodile, of 13 inches, made by my youngest son ; but after being 

 apprized of it by the large skeleton in the Museum, of 12 feet 4 inches, Paris 

 measure, on looking at my own when I returned home, I found them both 

 alike, and that those parts were not epiphyses ; of which however the transverse 

 processes of the neck, fig. 1 , deqonp, have all the appearance, though there is 

 no other epiphysis to be observed in the rest of the bones of that large skeleton. 

 When we compare the fossil vertebra, fig. 5, with those now in the Museum, 

 we shall find the epiphyses abcd analogous to abed, fig. 4, being the real epi- 

 physes in the vertebra of a young porpoise. 



I procured, in London, the largest vertebrae of the neck of a turtle I could 

 get, and prepared two of them as in fig. 3, in which, as along the back of that 

 singular creature, I found the transverse divisions acdf: of all which I have not 

 seen a single instance among the dorsal spinae from St. Peter's mountain, one of 

 which consists of 7 3 another of 12, and a third of 14 vertebrae. Some of the 

 vertebrae have, I acknowledge, an inferior process, as in the crocodile, Im, fig. 

 1. Of these I have sent also 2 to the Museum. The ostrich and the turtle 

 mydas have such processes, but no quadruped I know of. 



The articulation of the vertebrae with each other, by the surfaces of the 

 bodies themselves, is entirely different, not only from that of the crocodile, but 

 from that of all the cetaceous fishes I have ever seen : and I dare venture to 

 assert, I have seen a great many, exclusive of those in my collection. The 

 anterior part of the Maestricht vertebrae is more or less triangular and hollow, 

 as in fig. 5, CDL. The posterior ab is convex. Both these surfaces are very 

 smooth, as if they had been covered with a very thin cartilage, and moved on 

 each other, without being united by an elastic lamella, as in all quadrupeds and 

 cetaceous fishes ; in which the vertebrae have on both the surfaces a round 

 brim, or circular edge, ahib, by means of which the ligaments are connected, 

 and a fiat hollow surface within, as hi, fig. 4, for the elastic pulp that is between 

 them. 



^5. The dentition is so singular in these fossil jaw-bones that it deserves a 

 particular description. In all quadrupeds, as in man, the teeth which appear 



