A BH 



BM or; 



BP.2 BB Bf\.i 





CH BR.+ BR.3BR,2BKj 



Fig. 32. A. — The skull of a i2-mm. tadpole, seen from 



THE RIGHT SIDE. THE NOTOCHORD, THE BRAIN, AND THE ENTIRE 

 HEAD ARE REPRESENTED IN OUTLINE, IN ORDER TO SHOW THE RE- 

 LATIONS OF THE SKULL TO THEM. 



B. — The same skull from the dorsal surface. The lower 



JAW and the HYOIDEAN AND BRANCHIAL BARS ARE OMITTED. 



C. — Same skull from the ventral surface. (A, B, and C 

 are all from Marshall.) 



BB, basi-branchial. B //, roof of hind-brain. B M^ roof of mid-brain. 

 57?.l, B R.2, B/?.S, B RA, first, second, tbird, and fourth branchial bars. BS, 

 cerebral hemisphere. CH, notochord. /'.' (T, auditory capsule. H B^ basihyal. 

 HO, urohyal. H Q, articulation of ceratohyal with quadrate. // A", ceratohyal. 

 y L, lower jaw. y i^, upper jaw. LI, upper lip. Ly^ lower lip. LL, lower 

 labial cartilage. LL\ upper labi.^l cartilage. M C, Meckel's cartilage. PN, 

 pineal body. Q, quadrate. (9 (9, orbital process of quadrate, ^Z*. palato-ptery- 

 goid process. Q R., connection of quadrate with trabecula. R C, paracordal 

 cartilage, R L, trabecula cranii. SA, membranous patch in which stapes is de- 

 veloped later. X, choroid plexus of third ventricle. 



86 



