THE ELASMOBRANCII FISHES 



59 



-t.< 



Fig. 66. CraniuiJi of Ileterodontus francisci, lateral view. (Diniean Donning, del.) 



,5p.C. 



Fig. 67. Skull of Mcterodontus francisci (articulate). (Duncan Dunning, del.) 



a.c, auditory capsule; cli., ceratohyoid; ?., labial cartilage; f.op., foramen for profundus 

 nerve; f.r-a., foramen for ramus anastomoticus artery; /.//, optic foramen; f.IV, troch- 

 learis foramen; f.VII, foramen for hyomandilmlaris branch of facial nerve; f.X., foramen 

 for tenth nerve ; lim., hyomandibula ; md., mandible ; o.f., orbital fissure ; o.p., optic pedicel ; 

 po.o., postorbital process; p-il-, palatoquadrate cartilage: pr.o., preorbital process; sp.c, 

 spiracular cartilage. 



