RL 



JL 



BRa BB BB..I 



HO H<? HR Q MC 



LL 



RL 



LL 



FIG. 34 BIS. 



A. The skull of a 12 mm. tadpole, seen from the right side, x 30. 



B. The same skull from the dorsal surface. The lower jaw and the 

 hyoidean and branchial bars are omitted, x 30. 



C. The same- skull from the ventral surface, x 30. 



BB, basibranchial ; BH, roof of hind brain; BM, roof of mid-brain ; BR.I, 

 BR.a, BR-3, BR.4, first, second, third, and fourth branchial bars; BS, cerebral 

 hemisphere; CH, notochord ; EC, auditory capsule; HB, basihyal; HO, 

 urohyal ; HQ, articulation of ceratohyal with quadrate; HR, ceratohyal ; 

 JL, lower jaw ; ju, upper jaw ; LI, upper lip; LJ, lower lip; LL, lower labial 

 cartilage; LU, upper labial cartilage; MC, Meckel's cartilage; PN, pineal 

 body; Q, quadrate; Qp, orbital process of quadrate; QP, palato-pterygoid 

 process; QR, connection of quadrate with trabecula; RC, parachordal 

 cartilage; RL, trabecula cranii;.SA, membranous patch in the outer wall of 

 the auditory capsule, in which the stapes is developed at a slightly later stage. 

 X, choroid plexus of third ventricle. 



To face p. 141. 



