DEVELOPMENT OF THE SKULL IN THE OSTEICH TEIBE. 179 



Descbiption op the Plates*. 



PLATE VII. 



Struthio camelus, ''^ A." One-third of incubating period. 



Fig. 1. Primordial skull, seen from above; 3 diameters: b.o. basioccipital ; n.c. noto- 

 chord; e.o. exoccipital ; f.m. foramen magnum; s.o. superoccipital ; 9. 9th 

 nerve; a.s.c. anterior semicircular canal; 5. trigeminal nerve; a.s. alisphe- 

 noid ; i.e. internal carotid; pt.s. pituitary space; p.cl. posterior clinoid ; 

 a.cl. anterior clinoid; 2. optic nerve; o.s. orbito-sphenoid ; cr.ff. crista galli; 

 eth. ethmoid; p.p. pars plana; al.e. aliethmoid; cd.s. aliseptal; al.n. ali- 

 nasal; p.n. prenasal. 



Fig. 2. Vertical section of the same skull ; 3 diameters : o.c. occipital condyle ; 8. 8th 

 nerve ; 7. 7th nerve ; b.s. basisphenoid ; s.c. sinus canal ; a.p. anterior ptery- 

 goid process ; p.s. presphenoid ; r.b.s. rostrum of basisphenoid ; p.e. perpen- 

 dicular ethmoid ; s.n. septum nasi ; 1. olfactory nerve. 



Fig. 3. Side view of entire skull ; 3 diameters : m.t. membrana tympani ; n.g. nasal 



• gland; d. dentaiy; s.a. surangular; a. angular; ar. articular. 



Fig. 4. Lovi^er view of ditto ; 3 diameters : b.t. basitemporal ; p.g. pterygoid ; pa. pala- 

 tine ; p.v. prevomer ; v. vomer. 



Fig. 5. Upper view of the same skull; 3 diameters: q, quadrato-jugal ; j. jugal; 

 n. nasal; I. lacrymal; p.x. premaxillary. 



Fig. 6. End view of the entire of skull of the same ; 3 diameters : fo. fontanelle ; 

 f. frontal ; p. parietal ; sq. squamosal ; q. os quadratum ; p.s.c. posterior semi- 

 circular canal ; h.s.c. horizontal semicircular canal. 



Fig. 7. Os hyoides of the same ; 3 diameters : c.h. cerato-hyals ; b.h. basi-hyal ; u.h. uro- 

 hyal; th.l. lower thyro-hyal; th.2. upper ditto. 



PLATE VIII. 



Fig. 1. Side view of skull of Struthio camelus, "B. ;" 2 diameters. 



Fig. 2. Lower view of the same; 2 diameters: st. stapes; p.r.p. posterior pterygoid 

 process. 



Fig. 3. Upper view of skull of Sfrutkio, " B. ;" 2 diameters. 



Fig. 4. End view of skull of Struthio camelus, "B. ;" 2 diameters: p.c.f. posterior con- 

 dyloid foramen ; op. opisthotic. 



Fig. 5. End of mandible, seen from above, ofStruthio, "C. :" pn. pneumatic foramen. 



* The cartilage-hones are distinguished from the splint-hones in the Plates by being sparsely dotted; the 

 cartilage itself is finely and closely dotted, and the membranous spaces are cross-barred. 



2c2 



