Ichthyopsida 



449 



Nasal 

 capsule 



^--Premaxillary-. 

 ^ Maxillary..^ 

 Vomeropalatin 

 Nasa 



-Prefrontal 

 -Frontal 



Orbitosphenoid 

 Parietal 

 _„ Pterygoids 

 Squamosal 

 •^Cy^ ,Quadrate 



.Orbitosphenoid 



Operculum 



Dorsal 



Columella 

 Operculum 

 Exoccipital 



Fig. 346. Two views of the skull of Cryptobranchus alleganiensis, an aquatic 

 salamander. Dermal bones are stippled heavily. Cartilage bones are stippled lightly, 

 except for portions of the orbitosphenoid and quadrate and the exoccipital. The 

 isolated semilunar bone (upper left) is the eye capsule. Other cartilaginous parts 

 are columella, operculum (stapes), nasal capsule, and otic capsule. In both figures 

 the dermal bones have been retained on the right side of the skull and removed on 

 the left. (After Wilder: "History of the Human Body," New York, Henry Holt 

 & Co., Inc.) 



P. G» 



R. Gl. 



Can. 



Fig. 347. Section perpendicular to the surface of the skin; from the dorsal sur- 

 face of the tail-base of Plethodon cinereus, showing three types of integumentary 

 glands. (Cap.) Capillary; (D.) dermis; (Dt.) duct of exhausted granular or poison- 

 gland; (E.) epidermis; (H.G1.) hedonic gland (cut to one side of main axis); I M.< rl. I 

 mucous gland; (P.) melanophore; (P.G1.) poison-gland; (R.G1.) developing poison- 

 gland. (By permission from "Biology of the Amphibia," by G. K. Noble, copy- 

 righted 1931. McGraw-Hill Book Co., Inc.) 



