Fig. I Gill and arm buds indicated by lateral depressions ; head 

 and tail distinct. Yolk mass confined to region of the lower abdomen. 

 May 27th. 



Fig. 2 Three gill buds on right side separate, two on left side 

 and coalesced; arm buds well formed. Pigment in irregularly 

 shaped flecks confined to the back of head, trunk and tail. Embryo 

 active within the gelatinous envelops of egg. Eyes prominent with 

 pupils well developed. June 2d. Length of embryo 7.3 mm. 



Fig. 3 , Marked development of the gills with indications of 

 fringes. Body compressed back of the head and yolk confined to 

 anal region of abdomen. Color pattern developing along sides of 

 back and tail. June 4th. Length 9.4 mm. 



Fig. 4 Gills completely developed and functional; hands with 

 three fingers and legs with indications of developing toes. Color 

 pattern brilliant; light and dark grays predominating with inter- 

 spersed patches of yellowish green and orange. June 6th. Length 

 12.6 mm. 



Fig. 5 Larva just released from egg envelops. Body and tail 

 compressed and from above, wedge-shaped. Fingers fully developed ; 

 toes partly so. Larvae in this stage when placed in water swim 

 freely. June 12th. Length 13.8 mm. 



Fig. 6 Reduction of gills 7 days after leaving the egg in larva 

 reared from eggs kept in damp moss. Larva kept in moss saturated 

 with water retained the gills fully developed for 24 days (counting 

 period passed in egg), then died. Adult proportions of body and 

 limbs being acquired in this stage. June 19th. Length 15 mm. 



Fig. 7 Detail of gill at height of development showing the two 

 rows of fringe. Direction of flow of blood indicated by arrows. 



