DESCRIPTION OF THE PLATES. 



17 



of the crown of a tooth of the Labyrin- 

 thodon leptognathus ; both magnified 30 

 linear diameters, Original. 



PLATE 64. 



Portion of a transverse section of the great 

 tooth of the Labyrinthodon (Mastodon- 

 saurus) Jaegeri, magnified 30 linear dia- 

 meters, a, Pulp-cavity ; b, dilated termi- 

 nation of one of the radiated fissures ; c, 

 inflected fold of cement; d, termination 

 of the fold. Original. 



PLATE 64. A. 



Fig. 1. — A reduced view of a section 

 through the middle of the crown of the 

 same tooth similarly magnified, a, Ra- 

 diating fissures from the pulp- cavity ; b, 

 converging folds of ossified capsule ; b', 

 shorter folds of ditto. Fig. 2. A single 

 lobule of dentine, magnified 350 linear 

 diameters, a, basal subdivision of pulp- 

 fissure ; b, thin layer of cement. Fig. 3. 

 Terminations of two dentinal tubes, 500 

 linear diameters. Original. 



PLATE 64. B. 



Fig. 1 . — Anterior tusk, lower jaw of Laby- 

 rinthodon pachygnathus. Fig. 2. Half of 

 the transverse section across the dotted 

 line in fig. 1, magnified 50 diameters (a 

 reduced view). a, Fissures radiating 

 from pulp-cavity ; b, converging folds of 

 ossified capsule ; C shorter folds of ditto. 

 Fig. 3. Transverse section of base of 

 tooth of Ichthyosaurus communis, a, Fis- 

 sures radiating from pulp-cavity ; b, ex- 

 ternal cement. Original. 



PLATE 65. 



Fig. 1. — Base of cranium and teeth of a 

 Ccecilia (Epicrium bivittatum). Fig. 2. 

 Side view of skull and teeth of ditto. 

 Fig. 3. Side view of skull and teeth of 

 Amphisbcena alba. Fig. 4. Base of cra- 



VOL. II. 



nium of ditto. Fig. 5. Half of base of 

 cranium of Ophisaurus ventralis. Fig. 6. 

 The same of the Tiger -boa (Python tigris). 

 Fig . 7. Side-view of the skull of the Tiger- 

 boa ; a, intermaxillary ; b, maxillary ; c, 

 palatine ; d, pterygoid; e, tympanic pedicle ; 

 /. mastoid. Fig. 8. Skull and teeth of a 

 Rattle-snake, (Crotalus horridus) ; b, 

 maxillary bone and poison fang ; c, pa- 

 latine ; d, pterygoid teeth. Fig. 9. Maxil- 

 lary, palatine and pterygoid bones and 

 teeth: a bristle is passed through the ori- 

 fices and canal of the poison- fang. 

 Fig. 10. Base of poison-fang. Fig. 11. 

 Longitudinal section of poison-fang; a, 

 pulp-cavity, b b, poison-canal. Fig. 12. 

 Dissected head of Trigonocephaly Ian- 

 ceolatus : a, base and common stem of 

 the pinnate lobes of poison-gland ; b b, 

 capsule of the gland laid open ; c, poison 

 duct, the dotted line shows its course to 

 the fang ; d. nasal salivary gland ; e, la- 

 bial mucous glands. Fig. 13. Base of 

 skull and lower jaw of a Cobra-di-capello; 



a, intermaxillary ; b, maxillary and poi- 

 son-fang ; d, pterygoid with non-veno- 

 mous teeth. Fig. 14. Hydrophis striatus: 



b, maxillary teeth. Fig. 15. Dissected 

 head of Hydrophis schistosa : a, anterior 

 temporal muscle ; b, middle temporal 

 muscle ; c, posterior temporal muscle ; 

 d, digastric ; e, articulo-maxillary tendon 

 which expands, at /, upon the sac of the 

 poison-gland. Cuvier and Cantor. 



PLATE 65. A. 



Fig. 1. — Natural size and magnified trans- 

 verse section of a poison-fang ; a, pulp- 

 cavity ; b b, dentine ; c, thin exterior 

 cement uniting the folds that include the 

 poison-canal. Fig. 2. The united folds 

 of the previous section, magnified 500 

 linear diameters ; c, cement. Original. 



b 



