NECTURUS MACULATUS 403 



(b.) Brain case. 



1. Frontal. 



'2. Parietal. 



3. Parabasal, 

 (c.) ITjjper jaw. 



1. Maxillary arch, 

 a. Premaxillary. 



'2. Palatopterygoid arch. 



a. Vomer. 



b. Palatopterygoid. 

 The Visceral Skeleton. . 



(a.) General morphology of the arches, 

 (b. ) Mandible. 

 1. Dentale. 

 •J. Angulare. 

 3. Spleniale. 

 (c.) Hyobrauclual apparatus, 

 (d.) Suspensorial relations of the hyoid. 

 The Free Sense Capsules. 

 (a.) Nasal capsule, 

 (b.) Optic capsule. 

 The Teeth. 

 Comparison of Nomenclature. 



General Description of the Skull and its Parts. 



The term " skull" is used here iu its most restricted sense and does not incltide either 

 the mandible, the h^'obranchial apparatus or the nasal and optic capsules. These elements 

 are for the most pai-t easily detachable from the firmlv consolidated sktdl. and are thus, in 

 the anatomical sense, not to be included with it. A single exception may be made in the 

 case of the nasal capsule with regard to wliich the usage of authors differs, since, although 

 anatomically distinct in Necturus, it belongs genetically to the primordial skull. Wieders- 

 heim, for example. wh(j is correct from the morphological standpoint, figures it in his 

 drawing of the sktdl, while both W. K. Parker (in Proteus) and Huxley fail even to lind 

 it. In this paper it will be omitted from consideration at present to receive special treat- 

 ment later on. 



The skull, then, denuded of all its extraneous elements, will present an appearance 

 much as is givea in figures 2 and o (plate 63). The general outline suggested a pentagon 

 to Huxley, but in orcU'r to see it as such, one should imagine the ligaments restored that 



