STAGE 60 Age +/- 46 d.

Ext. Crit.: N. olfactorius still longer than bulbus olfactorius. Guanophores appearing on lower jaw (adult skin area). Openings of gill chambers still wide. *Distal half of fingers stretched forelimb extending beyond base of hindlimb*; forelimb still situated behind level of heart. Adult skin area of base of forelimb covered with guanophores; anterior border of adult skin area on abdomen sharper, reaching up to heart.

Int. Crit.: *Well defined stratum corneum formed on upper jaw*; appearance of horn papillae in the other adult skin areas; strip of larval skin between trunk and hindlimb areas of metmorphosing skin disappeared for greater part. *Cross section area of largest lumbar motor column nuclei of spinal cord 6 x that of average adjacent non-motor nuclei*; neurocoel circular in cross section. *Naso-lachrymal duct opening in skin cranial to eye*. Rudiment of gland of Harder formed anterior of eye.

*Appearance of cartilago obliqua and prc. praenasalis superior; formation of praemaxillae and septomaxillae; appearance of dentale and outer lobe of goniale*; beginning of reduction of ethmoid plate and flanges; arytenoids chondrified. M. genio-hyoideus segregated into pars medialis and pars lateralis. First indications of occipito-vertebral joint formation; tissue connecting 1^st and 2^nd pair of ribs with corresponding vertebrae chondrifying; *cranial portion of 13^th pair of vertebral arches fused with urostyle*; primary marrow cavities in basal portions of vertebral arches; *chondrification of dorsal perichordal tube extending vertebrally down to 12^th pair and intervertebrally down to 11^th pair of vertebral arches*. *Paired anlage of sternum partially procartilaginous*. *Ossification starting in pubis; paired epipubis procartilaginous*. Complete differentiation of hindlimb musculature. 1^st and 2^nd nephrostome of pronephros fused; Wolffian duct between pro- and mesonephros showing signs of degeneration.

*Third row of tooth germs formed*. Middle ear anlage a bilobed vesicle.