86 FISHES. 



2. Mesencephalic arch, composed of basisphenoid, ali- 

 sphenoid, parietal, aud mastoid. 



3. Froscncephalic arch, composed of presphenoid, orbito- 

 sphenoid, frontal, and postfrontal. 



4. Bhinencejjhalic arch, composed of vomer, prefrontal, and 

 nasal. 



The hcemal arches in the same order of succession are : — 



1. Scapular or scapulo-coracoid arch, composed of supra- 

 scapula, scapula, aud coracoid ; its appendage consists of the 

 ulna, radius and carpal. 



2. Hyoid or stylo-hyoid arch, composed of stylo-hyal, epi- 

 liyal, ceratohyal, basihyal, glossohyal, and urohyal ; its ap- 

 pendage is the branchiostegals. 



3. Mandihtdar or tyinpano-mandibidar arch, composed of 

 epi-, meso-, pre-, and hypo-tympanic, and the bones of the 

 lower jaw ; its appendage consists of the pneoperculum and 

 the other opercles. 



4. Maxillary or palcdo-maxillary arch, composed of pala- 

 tine, maxillary, and premaxillary ; its appendage consists of 

 the pterygoid and entopterygoid. 



Parts of the splanchnoskeleton are held to be the ear-capsule 

 or petrosal and the otolite, the eye-capsule or sclerotic, the 

 nose-capsule or " ethmoid " and turbinal ; the branchial 

 arches. 



The bones of the dermoskelcton are the supratemporals, 

 supraorbitals, suborbitals, and labials. 



B. In the second method of classifying the bones of the 

 skull prominence is given to the facts of their different origin 

 as ascertained by a study of their development. The parts 

 developed from the primordial skull, or the cartilaginous case 

 protecting the nervous centre are distinguished from those 

 which enclose and support the commencement of the aliment- 

 ary canal and the respiratory apparatus, and which, consisting 

 of several arches, are comprised under the common name of 



