356 



TRANSACTIONS OP THE 



feces, exist in very few of them; these serve, however^ 

 to demonstrate an altachmeut both to the bodies and 

 transverse apophyses of the vertebrse. 



These bones are more or less cylindrical, although 

 occasionally considerably compressed, and like the ribs of 

 most marine animals, are destitute of cellular structure. 

 In some instances they appear to the naked eye quite 

 compact and solid ; but the variously fractured surfaces 

 of others display a peculiar structure, the whole cylinder 

 being composed of eccentric laminae- : this appearance is 

 accurately represented, pi. 24, fig. 4. The diameter 

 of the largest specimens does not exceed three inches. 



There are a few spinal extremities of the false ribs, 

 sometimes with single, at others with double articulating 

 fiicets. The shafts of these are considerably curved. 



Humerus. PL 22, fig. 6. 



One arm bone, which constituted a portion of this ske- 

 leton, possesses unique characters. The complexion of 

 this bone is of a much darker tint than the other bones, 

 owing probably to its accidental position in the rock. 

 The head, neck and tubercles of this bone bear a strik- 

 ing analogy to those parts in the human skeleton. Its 

 shaft is depressed, and particularly so as you depart 

 from the proximate extremity, for two-thirds the length 

 of the bone, where it is flattened, and produced out- 

 wards, to form a large depressed external condyle, when 

 the bone becomes more cylindrical, and gradually atte- 

 nuated laterally to the distal extremity, which termi- 

 nates in a ginglymus articulation. The structure of this 

 portion of bone leaves no doubt that the superior extre- 

 mity of this animal assumed the form and functions of a 

 lin or paddle ; but a remarkable feature in this bone, is 

 its extreme smaliness in proportion to other portions of 

 the skeleton, which renders it certain that the animal 



