204 ON THE FOSSIL BONES OF PACIIYDEHMATOUS QUADRUPEDS, 



n. The germ of the back tooth, still inclosed in its membranous cap* 

 sule, and this latter lodged in a cavity of the back jaw. 



0. The nerve of the fifth pair, which gives filaments to the capsules 

 •of the teeth, and to their pulpy nuclei. 



These same two teeth are represented in a large size, 7;/, 9, /g, 1. 

 and 2, 



Fig. 1 . Is the tooth in action ; «, b, the portion of its lamella? already 

 worn down ; b, c, the portion still untouched ; d, e, f, its roots, which 

 are sunk between the productions of the alveolus, g, h, i. 



All the inner surface of the roots, and of the base of the body of 

 the tooth has been removed, to show the pulpy nucleus, k, I, m. 



As the body of the tooth is almost entirely shut and filled, the little 

 transverse walls, n, 0, p, q, r, s, are almost entirely shortened and com- 

 pressed ; but to make up for this, the pedicles t, u, v, x, which serve for 

 the formation of the roots, are already considerably lengthened. 



Fig. 2. Is the germ of the back-tooth, drawn with its capsule from 

 the cavity of the back jaw. 



a. b. Remainder of the periosteum of the ah^eolus, 



c, d. Anterior part of the external membrane of the capsule. 



e, f. Portion of this external membrane, detached and thrown down, 

 to show the inner membrane g, h, i. 



k, k, k, k, &c. Transverse productions of this inner membrane, 

 which separate the lamellae of the tooth and the gelatinous walls on which 

 these lamelloe are formed. 



The portion of the membrane which united these productions are 

 removed, in order to show the lamellae of the tooth which they covered. 



i, I, I. The body of the pulpy nucleus of the tooth. 



m, m, m, m, &c. Its productions, or the small transverse walls which 

 it sends between the productions of the capsule, and on which the 

 Mmellse of the tooth are formed. 



n, n, 71, n, &c. Lamellae called bony, transuded by these little walls 

 which envelope them, and the aggregate of which is to form the tooth. 



The posterior ones are much shorter, and do not envelope so complete- 

 ly their little walls, because the transudation commences later behind. 



0, 0, 0, 0, &c. The enamel deposited on these lamellae, by the inter- 

 nal surface of the capsule. There is much less of it in the posterior 

 lamellae, for the same reason. 



In the part d, g, h, the cortical substance has alreadj' covered the 

 enamel, and agglutinated the lamellae together. 



p, p, p. The solutions of continuity which separate the commence- 

 ment of the pedicles of the roots. 



Fig. 3, Is the middle part of this same germ, seen at its posterior 

 surface. 



G fl. Its base seen shortened. 



b. One of the small transverse walls. 



c. The lamella called osseous which still envelopes only its dentuli. 



d. A dentulus whose envelope is not yet joined to the others. 



e. e, e, e. The enamel which commences to be deposited on this la- 

 mella, 



/. Remainder of the capsule. 



