PLATE I 



THE CRANIUM OF CHLAMTDOSELACHUS, WITH THE ANTERIOR END OF THE 

 VERTEBRAL COLUMN ATTACHED 



Fig. 1. Dorsal view of the cranium, natural size. 



af, articular facet for hyomandibular; an, ala nasalis; cp, cavum precerebrale; ecp, ectethmoidal process; ef, endolym- 

 phatic fossa; es, eyestalk; fp, foramen for nervus profundus; id, interdorsal; pc, preorbital canal or foramen; pop, 

 postorbital process. 



After Allis, 1923, Fig. 9, pi. VIII. 



Fig. 2. Ventral view of the cranium, natural size. 



aop, antorbital process; ha, bulla acustica; fie, foramen for internal carotid artery; /so, foramina supraorbitalia; naf, nasal 

 fontanelle; pb, palatobasal ridge. 



After Allis, 1923, Fig. 11, pi. IX. 



Fig. 3. Lateral view of the cranium, natural size. 



af, articular facet for hyomandibular; bd, basidorsals; fe, foramen for efferent pseudobranchial artery; ff, foramen for 

 nervus facialis; fie, foramen for internal carotid artery; fo, foramen for nervus opticus; foe, foramina for occipital nerves; 

 fom, foramen for nervus oculomotorius; fp, foramen for nervus profundus; ftr, foramen for nervus trochlearis; id, inter- 

 dorsals; n, nodule of cartilage; naf, nasal fontanelle; one, orbitonasal canal; pb, palatobasal ridge; pe, preorbital canal, or 

 foramen; r, rostrum; sbd, supra-basidorsals; tpf, trigemino-pituitary fossa. 



After Allis, 1923, Fig. 8, pi. VIII. 



