91 



facilitate this inquiry, I may remark, that a very slight examination 

 of a vertebra is sufficient to determine, whether the epiphysis has, or 

 has not been detached ; as in the former case the surface is marked 

 hy deep ridges and furrows diverging from the centre towards the cir- 

 cumference; whereas in the latter, if the animal was of moderate size, 

 the marking consists of concentric lines, answering to the attachments 

 of the intervertebral substance ; and if the individual was very large, 

 these concentric lines are exaggerated into concentric furrows ; and 

 whether the attachments of the intervertebral substance be marked 

 by concentric lines or by concentric furrows, a considerable portion of 

 the central part of the bone, where it had been in contact with the in- 

 ternal substance of the intervertebral ligaments, is quite destitute of 

 this marking, and presents a striking contrast to the rest of the sur- 

 face. 



I am not aware that the true cause of this remarkable difference 

 between the markings on the extremities of the vertebrae of the 

 cetacea has been before explained. 



It may not be uninteresting to add, that the cranium of the Del- 

 phinus diodon in my possession, and both those in the Museum ot 

 the College of Surgeons, present, in a very remarkable manner, the 

 want of symmetry between the right and the left sides of the cranium, 

 which was first observed by Meckel in the skulls of the cetacea. 



Note. — Since the preceding notice concerning the hock-joint of the horse, was submitted to 

 the Academy, I have had an opportunity of examining two horses affected with string-hah, and 

 am inclined to attribute the disease to a spasmodic affection of the flexors of the limb gene- 

 rally, rather than to any derangement in the structure of the hock-joint. It may be right to 

 mention that the following authors on Comparative Anatomy, and the Anatomy of the Horse, 

 have been searched, but they contain no notice of the peculiarity in the structure of the hock- 

 joint, above described. — Macartney, Cuvier, Carus, Blumenbach, Meckel, Clater, Blaine, 

 Stubbs, Percivall, Boardman, White, Lawrence, Osmer, Home, Bourgelat, 



