54 ARTllULl DENDY. 



(3) Five digits appear as blunt projections on the margins of 

 both hand and foot. 



(4') The hyoinandibular cleft has completely closed. 



I am inclined to believe that pigment first appears in the 

 parietal eye at this stage, but the sections are not sufficiently 

 well preserved to be conclusive. 



Stage R (figs. 104—107). 



Owing to its long duration this stage is represented in my 

 collection by a large number of embryos, viz. : 



2 — 4, collected on Stephens Island on July 1st, 1897, and removed from the 



eggs about a week later. 

 14,1 — 14.8^ collected on Stephens Island on February 4th, and removed from 



the eggs on March 8th, 9th, 12th, and 14th, 1898. 

 151 — 158, removed from the eggs on April 5lh, 1898. 

 159—161, removed from the eggs on May 12lh, 1898. 

 162, removed from the egg on June 24th, 1898. 

 169, 170, removed from the eggs on June 14th, 1898. 



I have also a number of eggs, doubtless containing embryos 

 of this stage, as yet unopened. 



In tliis stage the embryos pass the winter, entering upon it 

 in February or March, and developing very slowly through the 

 winter months. Embryos removed from the eggs in March 

 almost exactly resemble in external characters those removed 

 in July, the differences not being, in my opinion, sufficient to 

 necessitate a separation into distinct stages. The external 

 differences concern chiefly the appearance of the head as 

 viewed from above, the younger embryos showing distinctly 

 the optic lobes and cerebral hemispheres through the integu- 

 ment, while in the older embryos (fig. 105) these are no longer 

 visible. As regards internal differences I have not made a 

 sufficiently detailed study to say much, but it is noteworthy 

 that while in the younger embryos the parietal eye still lies 

 close up against its so-called " stalk," in the older ones it is 

 separated by a considerable interval from tlie blind end of the 

 latter, and the nerve of the parietal eye l)as made its appear- 

 ance. It is also noteworthy that whereas at the commence- 



