Motor System — Muscles and Skeleton 



119 



Fig. 116. Diagram of early elasmobranch skull, (bp) Basal plate; (c) trabecular 

 cornu; (fl) foramen lacerum; (ga i ~ h ) gill arches; (gc) gill cleft; (h) hyale; (hm) hyo- 

 mandibula; (I 1 , P) upper labials; (//) lower labial; (m) mandibular (Meckel's) 

 cartilage; (nc) nasal capsule; (oc) otic capsule; (of) orbital foramen; (ov) occipital 

 vertebrae; (pq) pterygoquadrate; (s) suspensor ligament; (sp) spiracle; (si) spheno- 

 lateral; (t) trabecula; (v) vertebrae; (I-VII) visceral arches; (1-10) cranial nerves. 

 (Courtesy, Kingsley: "Comparative Anatomy of Vertebrates," Philadelphia, The 

 Blakiston Company.) 



Fig. 117. Ventral view of cranium and visceral arches of skate (Raia) after 

 Gegenbaur. (cp) Copula; (h) hyoid; (hm) hyomandibula; (la) upper labials; (mk) 

 mandibular (Meckel's) cartilage; (nc) nasal capsule; (pq) pterygoquadrate; (r) 

 rostrum. (Courtesy, Kingsley: "Comparative Anatomy of Vertebrates," Phila- 

 delphia, The Blakiston Company.) 



