38 ZOOTOMY. 



angle of the hyomandibular by a band of fibrous tissue, the 

 inter-hyal ligament, and made up of three segments, 

 an epi-hyal (e.hy) above, cerato-hyal {c.hy) next, and 

 hypo-hyal {h.hy) below. 



41. The five branchial arches (Fig. 10), each of which 

 consists primarily of four segments, which are, counting from 

 above downwards, pharyngo-branchial, epi-branchial 

 {e.br), cerato-branchial (c.br), and hypo-branchial 

 {h.br). The fourth and fifth pharyngo-branchials unite 

 with one another and with the fifth epi-branchial to form a 

 single cartilage: the first hypo-branchials {h.br.i) unite 

 with one another in the middle hne, forming a slender 

 transverse bar of cartilage just posterior to the lower jaw : 

 and the fifth hypo-branchials {h.br. 5) also unite with one 

 another to form a large baSi-branchial plate, produced 

 anteriorly into two processes, and lying immediately dorsally 

 to the heart and ventral aorta. 



VIII. In the shoulder girdle, note 



42. The complete union of the two halves of the girdle 

 in the middle line below, and the attachment of each half 

 above to the median dorsal ridge of the anterior vertebral 

 plate (Fig. 10). 



43. The three convex articular surfaces or glenoid 

 facets (Fig. 10, gl. i — 3), situated on the external surface 

 of each half of the shoulder girdle, and serving for the 

 attachment of the three chief divisions of the fin (see 

 §§ 46 — 48). The part of the girdle which lies to the dorsal 

 side of the glenoid facets is the scapular region {sc, s.sc), 

 — that on the ventral side the coracoid region (cr). 



44. The three large apertures or fontanelles which 

 perforate the shoulder girdle : the anterior of these is 

 the scapulo-coracoid fontanelle (Fig. 10, s.c.f) : the 

 postero superior, the scapular fontanelle, and the 



