ANATOMY OF VERTEBRATES. 103 



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

 (Fig. 81, N, H.) The neural arches are- 



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

 N II. Mesencephalic arch (5, 6, 7, s) ; 

 N in. Prosencephalic arch (9, 10, 11, 12); 

 N iv. Rhinencephalic arch (13, u, is). 



The haemal arches are 



H i. Scapular arch (50-52) ; 



H II. Hyoidean arch (33-43) ; 



H in. Mandibular arch (28-32) ; 



H iv. Maxillary arch (20-22). 



The diverging appendages of the haemal 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 splanchnoskeleton which are inter- 

 calated with or attached to the arches of the true vertebral 

 segments, are- 



The Petrosal (IG) or ear-capsule, with the otolite, is"; 

 The Sclerotal(i7) or eye-capsule; 

 The Turbinal (19) or nose-capsule ; 

 The Branchial arches (45-49) ; 

 The Teeth. 



The bones of the dermoskeleton are- 



The Supratemporals (74) ; 

 The Postorbitals (72) ; 

 The Superorbitals (71); 

 The Suborbitals (73); 



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

 certain ganoid fishes. 



Such appears to be the natural classification of the parts which 

 constitute the complex skull of Osseous Fishes. 



