DESCRIPTION OF THE PLATES. 



In the following Plates the parts are of the 

 natural size, unless otherwise expressed. 



PLATE 1. 



Various forms of teeth in fishes : the names 

 of the genera are subjoined to each figure. 

 In part Cuvier and Vol.* in part original. 



PLATE 2. 



Fig. 1. — Head of a Myxinoid fish (Bdello- 

 stoma heterotrema) : a, basal pulp, sup- 

 porting b, palatal tooth ; c, tongue, sup- 

 porting the lingual dental plates ; d, 

 tendon of the great retractor muscle of the 

 tongue. Fig. 2. Head of Bdellostoma 

 hexatrema : a, palatal tooth ; b, Ungual 

 teeth. Fig. 3. Section of head of the 

 Myxine glutinosa, nat. size ; a, medulla 

 oblongata ; b, cartilaginous acoustic cap- 

 sule ; c, naso-palatine canal ; d, dental ma- 

 trix of lingual teeth ; e, lingual bone. Mai- 

 ler. | Fig. 4. Front view of labial and lingual 

 teeth of a Lamprey {Petromyzon marinus) . 

 Fig. 5. Vertical section of the head of 

 the same species shewing the labial teeth : 

 a, the palatal cartilage supporting the 

 large bicuspid tooth; b, the opposing 

 cartilage below, representing the under 

 jaw ; c, the lingual cartilage. Fig. 6. 

 A section of the persistent pulp, and 

 successive horny dental cones of the Lam- 

 prey. Original. 



PLATE 3. 



Forms of teeth in different genera of 

 Sharks. Agassiz.X 



PLATE 4. 



The same ; the view of the teeth of the 

 Scymnus is original. 



* Cuvier and Valenciennes, Histoire Naturelle des 

 Poissons, 4to. 1828, et seq. 



t Vergleichende Anatomie d»r Myxinoiden, 4to. 1835. 

 t Poissons Fossiles, fol. 1830. 



PLATE 5. 



Fig. 1. — A vertical section of the under 

 jaw of the Lamna, shewing a vertical row 

 of eight teeth and their various de- 

 grees of calcification. Fig. 2. A highly 

 magnified view of the primary and 

 secondary branches of a dentinal tube of 

 the tooth of a Lamna. Fig. 3. Fossil 

 tooth of Lamna elegans. Fig. 4. Front 

 view of the same tooth. Fig. 5. Fossil 

 tooth of an Otodus. Original, 



PLATE 6. 



Longitudinal section, magnified, of a fossil 

 tooth of Lamna elegans, shewing the rami- 

 fications of the vascular canals in the 

 vaso-dentine, which constitutes the body 

 of the tooth : the hard or unvascular 

 dentine covers it like enamel. Original. 



PLATE 7. 



A section of the preceding tooth, magni- 

 fied 500 linear times, showing the sub- 

 parallel dentinal tubes in the hard peri- 

 pheral layer of dentine, and the reticulate 

 dentinal tubes between the vascular 

 canals a & b. Original. 



PLATE 8. 



Fig. 1. — Under surface of the head of 

 the Saw-fish (JPristis antiquorum), show- 

 ing the rostral and maxillary teeth, 

 ^th nat. size. Fig. 2. Some of the upper 

 and lower maxillary teeth. Fig. 3. A 

 section of the part of the rostrum and 

 of one tooth, a. b, ossified part of rostrum 

 forming its socket; c, canal for vessels 

 supplying the teeth ; d, medullary cavity 

 of rostral cartilage ; e, granular skin or 

 shagreen. Fig. 4. A single rostral tooth ; 

 a, its posterior groove, into which the 

 process at the opening of the socket fits. 

 Fig. 5. Transverse section of the tooth. 

 Original. 



