344 MR. W. H. FLO'WEIl O^ THE OSTEOLOGY OF THE SPEHM-WHALE. 



tenth, and absent in the eleventh caudal vertebra; in the Yorkshire skeleton it is 

 indicated by a ridge in the eighth, and is completely wanting in the ninth ; so that in 

 this respect the Tasmanian specimen holds an intermediate position between the two 

 nortliem ones. 



On the hinder edge of the transverse process of the fifth caudal vertebra, close to its 

 origin from the body, is a deep notch, for the passage of a blood-vessel ; in the two fol- 

 lowing vertebrae this notch increases in depth, being continuous with a vertical groove on 

 the side of the body of the bone. In the eighth the notch is enclosed so as to form a 

 large oval foramen -^" by ■^" in diameter, perforating the base of the transverse process, 

 rather behind the middle of the centrum. In the ninth vertebra the foramen is placed 

 nearer the median line, and therefore still further enclosed in the bone. It is here and 

 in the succeeding vertebra nearly midway between the anterior and posterior extremity. 

 This foramen is an important feature in all the remaining caudal vertebrae, being found 

 even in the penultimate, and presents several peculiarities worthy of note. As before 

 said, it first appears as a distinct foramen in the eighth vertebra ; or it may rather be 

 described as a broad vertical gi-oove on the side of the centrum, bridged over for a space 

 of 2^" by the base of the short transverse process. In the tenth vertebra it has become 

 a canal, 7" in length ; but the lower opening is still placed on the side of the body of 

 the vertebra. In the eleventh the lower opening is placed at the angle between the 

 side and the inferior surface, 5" fi-om the opening of the canal of the opposite side. In 

 the twelfth they have moved toward the middle of the inferior surface, being separated 

 from each other only by a narrow bony septum (less than 1" in width). In tlie next 

 thi-ee vertebrae the septum is still narrower ; in the sixteenth it suddenly widens to 2" ; and 

 thence onward the inferior openings are gradually placed rather further from each other, 

 until in the last few vertebrae the canals have gained the lateral position they possessed 

 on their first appearance. In the meanwhile the upper orifices of these canals, advancing 

 up the sides of the bodies of the vertebrae, soon come to be placed on each side of the 

 middle of the upper surface, and maintain this situation to the end, only approaching 

 nearer to each other as the vertebrae diminish in size. 



The articular sui-faces for the chevron bones are remarkably large and prominent, 

 with elevated edges, and rough cup-like depressions in their middle. In many of these 

 depressions a small, loose, irregular epiphysial plate is lodged. The first caudal ver- 

 tebra has a pair of subcircular facets at its hinder edge, of which the left is considerably 

 the larger, though somewhat less prominent ; to these the first (ununited) haemapophyses 

 fit closely. In the Caithness Cachalot, these bones are ankylosed to the body of the 

 vertebra, though not meeting each other at their free ends. In the second veilebra, 

 the hinder facets are of larger size ; but none are developed on the anterior edge. In 

 the third, the facets on the anterior edge are slightly indicated, the posterior ones have 

 increased still more. In the following nine vertebrae, the two pairs of facets are well 

 developed, tlie anterior ones at first comparatively small, but towards the end of the 



