SO DEVELOPMENT OF THE SKELETON Of THE Tl'ATARA. 



PLATE III. 



SPHE50DON PUlfCTATCS. DEVELOPING SKULL, EARLIER STAGES- 



The figures on this Plate are of wax models reconstructed from microscopic sections, 

 the skeletal parts being alone represented. The fenestrae and interspaces in the 

 chondrocranium are for the most part occupied by membrane (not indicated), except 

 in so far as they transmit nerves and blood-vessels (cf. PL IV. fig. 10). 



., angular; ar., articular; A.*.', baaipterygoid process; c.', anterior semicircular canal; 

 .j auditory capsule ; c.r., coronoid ; d., dentary ; e.c., extrastapedial cartilage ; CM., external 

 ; e.o., exoccipital; epg~, epipterygoid ; e*., ethmosphenoidal plate; ex., extranasal; ex. 1 -*, 

 extranasal processes ; /. i.-xii., foramina for exit of cranial nerves ; fjm^ foramen for ophthalmic 

 branch of the carotid; f.e., ethmoidal foramen; /.i., interorbital fenestra; /./"., foramen for jugular 

 rein; /.., foramen magnum ; /.., lateral cranial fenestra; fr. t frontal; k. t hyoid; k.' } anterior 

 cornu of the hyoid ; A.*, posterior cornu of the hyoid ; t ji., internal nares ; j^ jugal ; mk., Meckel's 

 cartilage; nur., maxilla ; nur/, maxillary process; n.a.p., alinasal process ; r ., notochord ; a. c^ nasal 

 capsule; .c/, supranasal process; n.e.*, prenasal process; ./.', nasal fenestra; n.paj)., naso- 

 palatine process; n.p.p., naso-premaxillary process; *., nasal; n.r.p., inferior naso-romerine 

 process ; oc.c.. occipital condyle ; as., otosphenoidal plate ; a*. 1 - 5 , otosphenoidal processes; 

 p. t parietal ; pa., palatine ; par., parachordal ; />./., prefrontal ; py., pterygoid ; py.', pter _ 

 process ; p.o. y postorhital ; po.f., postf rental ; p.p., parotic process ; p.y-, pteiygo-quadrate ; 

 pt.y presphenoidal cartilage ; p*. t parasphenoid ; px. t premaxilla ; py'. pituitary foramen ; 

 q.. quadrate; 9.', otic process of quadrate; q.j.. quadrato-jugal ; SM., supra-angular: #*., snhnasal; 

 * A, interorhital septum ; s.mje., septo-maxillary ; *.o/, supraocciphal cartilage ; 4$p., splenial ; 

 y., sqnamosal ; tq.", posterior process of sqnamosal ; gM.. snprastapedial cartilage ; */., stapes ; 

 tf., transpalatine ; tr. } trabecula ; ro., Tomer. 



Pig. 1 *. SJafft P. Dtrtltrp'mg chondrocrawiiun : Left lateral aspect. The arrow indicates the 



direction of the longitudinal axis of the embryo as it lay coiled. 



Fig. 2 1 . Stage P. The tame : Ethmoidal, trabecular, and sphenoidal regions, dorsal aspect. 



Fig. 3 \ Stage P. Tkt same : Parachordal and auditory regions, dorsal aspect. 



Fig. 4. Stage Q. Developing ckodrocraitimm : Lateral aspect. 



Fig. 5. Stage Q. Developing skmU : Lateral aspect. x 8. 



Fig. 6. Stage Q. Developing ckomdrocraminm : Ventral aspect. 



Fig. 7. Stage Q. The **me .-Dorsal aspect, x 8. 



Fig. 8. Siage R. Developing ckondrocra*i*m : Lateral aspect. 



Kg. 9. Stage R. Developing ***# : Posterior aspect. x 8. 



Fig. 10. Stage R. Tke tame : Lateral aspect. 



Fig. 11. Stage R. Tke tame : Dorsal aspect. x 8. 



Fig. 12. Stage R. Tke smme : Ventral aspect. x 8. 



1 In these figures the uncoloured areas represent pro-cntflage. 



