ANATOMY OF VERTEBEATES. 103 



Each segment consists of a 'neural' and a 'liajmal' arch. 

 (Fig. 81, N, II.) The neural arches are — 



N I. Epenceiihalio arch (bones Nos. i, 2, 3, 4); 



N II. Mcsencei)halic arch (5, o), 7, s) ; 



N HI. Prosenccphalic arch (0, 10, n, 12); 



N IV. Ilhincncephalic arch (1.3, u, 15). 



The hremal arclies are — 



H I. Scapular arch (50-52) ; 



IT II. Hyoidean arch (38-43) ; 



H III. Mandibular arch (28-32) ; 



H IV. Maxillary arch (20-22). 



The diverging appendages of the hajmal arches are — 



1. The Pectoral (54-57) ; 



2. The Branchiostegal (44) ; 



3. The Opercular (34-37); 



4. The Pterygoid (23-24). 



The bones or parts of the splanchnoskeletou which are inter- 

 calated Avitli or attached to the arches of the true vertebral 

 segments, are — 



The Petrosal (le) or ear-capsule, with the otolite, ic"; 

 The Sclerotal(i7) or eye-capsule; 

 The Turhinal (i9) or nose-capside ; 

 The Branchial arches (45-49) ; 

 The Teeth. 



The bones of the dermoskeleton are — 



The Supratemporals (74) ; 

 The Postorbitals (72); 

 The Superorbitals ("i); 

 The Suborbitals (;3); 



The Labials (75), and others which will be pointed out in 

 certain ganoid fislies. 



Such appears to be the natural classification of the parts which 

 constitute the complex skull of Osseous Fishes, 



