IN THE VERTEBRAL COLUMN OF CARTILAGINOUS FISHES. 645 



lage, all pierced by holes, as if riddled ; in a word, with admirable regularity. 

 Sometimes, the total appearance seems homogeneous, though less hard in the in- 

 terior than at the surface."* 



Dr GRANT, in his " Outlines of Comparative Anatomy," published first in the 

 Lancet in 1833 and 1834, and afterwards as a separate treatise, adds but little to 

 CUVIER'S above description. In pointing out the progress of ossification, as we 

 advance higher in the scale of animated beings, he remarks, " you can easily per- 

 ceive this consolidation of the laminae in this Shark, and in several other speci- 

 mens of this animal that are before you, and still better in the Sturgeon ; indeed, 

 in the Sturgeon you have a beautiful illustration of this fact, that while the bodies 

 of the vertebrae remain perfectly united, transparent, soft, and cartilaginous, the 

 laminae and spinous processes, and the transverse processes themselves, have be- 

 come white, opaque, and ossified, and have received a larger quantity of the 

 earthy matters we have enumerated, than the bodies themselves."! 



The only other work on comparative anatomy, which has of late years ap- 

 peared in this country, is the very excellent one of JONES, entitled, " A General 

 Outline of the Animal Kingdom," and published in 1841. Relative to the verte- 

 brae of fishes he has the following remarks : 



" Even in tracing the modifications observable in the construction of the ver- 

 tebral column, we have a beautiful illustration of the progressive advances of 

 ossification, in this central portion of the osseous system. The spine of the Lam- 

 prey, although at first sight apparently entirely soft and cartilaginous, presents 

 already, in the arches which compose the spinal canal, and in the soft cord that 

 represents the bodies of the vertebrae, slight indications of an incipient division 

 into distinct pieces ; rings of ossific matter are distinguishable, encircling at inter- 

 vals the soft spinal cartilage upon which they perceptibly encroach, so that on 

 making a longitudinal section of the cord, it offers an appearance sketched in the 

 adjoining figure (Fig. 220, A). In a more advanced 220 



form of a fish's skeleton, as, for example, in the 

 Sturgeon, these ossified rings are found to have en- 

 larged considerably, and penetrate still more deeply 

 into the cartilaginous mass (Fig. 220, B). As the 

 bony rings thus developed approximate the centre, 

 it becomes more and more evident that they represent the bodies of so many ver- 

 tebree."t 



Further on he says: "The skeletons of the cartilaginous fishes (Chondrop- 

 rii) will require a distinct notice, inasmuch as they present very remarkable 



* GUVIER, Lemons d'Anatomie Compare, by DUMEKIL. Paris, 1835, vol. i., pp. 127-28. 



f GRANT, in Lancet for December 1833, p. 540. 



\ JONES, General Outline of the Animal Kingdom. London, 1841, p. 490. 



