402 HARRIS HAWTTTORXE WILDER OX 



all of the vertebrae, but is restricted to a certain region, approximately that of vertebra 

 8 to 18. 



It would seem important to investigate the development of transverse process and 

 rib in certain of the other vertebrae, for example the 2d and the 4th. Regarding the 

 sacral vertebra and its rib, as stated previously, Goppert's conclusion, which does not 

 allow a complete homology with the rest of the vertebral column, seems anatomically 

 improbable. 



The Skull a\d Visceral Skeleton. 



Anatomically, the bones of the head consist of (1) the skull in tiie restricted sense, 

 which includes the cranium, the ear capsules, and the upper jaw pieces, (2) the nasal and 

 optic capsules, uiid (o) the visceral skeleton, represented by the mandible, the hyohran- 

 chial apparatus, and the laryngeal cartilages. In point of tjrigin the elements are three 

 in number : (1) the primitive cartilage, still seen in the sense capsules, the primordial 

 cranium, and the most of the visceral skeleton ; (2) cartilage bones, or ossifications of 

 localized portions of the primary cartilage ; and (3) dermal bones of iutegmeutal origin, 

 investing the surface of the cartilage in skull and mandible. 



Although there are osseous elements from two sources, the proportion of unossified 

 cartilao-e left in the adult head is very great and compares in this respect with the condi- 

 tion seen in the Chondrostei rather than with that of other fishes or of most amphibians. 

 This large amount of cartilage is very suggestive of an embryonic or innnature form, and 

 suggests either the possibility which has already been frequently expressed, that Necturus 

 is in a sense a permanent larva, as is tlie case with the Axolotl, or that it is an exceed- 

 ingly primitive form, perhaps nearer the fishes than any other amphibian. 



An orderly treatment of this complex Ijit of anatomy is extremely difficult and may 

 perhaps be facilitated by the presentation of a classification of the suljject, which will be 

 adhered to in the later description. 



General Desckiption. 

 The Chonurocbanium. 

 The Osseous Elements. 



(a.) Otic and occiiiital regions. 

 1 . Pro-otic. 

 '2. ()|jisthotic. 



3. Exoccipital. 



4. Quadratum. 



5 and 6. Faraquadratum and opert'iiluni. 



