52 ARTHUR DENDY. 



phalon as a round white spot with a darker centre. The eye 

 itself lies just in front and to the left of this spot, and appears 

 as another round white spot, distinguished from the one behind 

 it by its double outline, the inner circle representing the out- 

 line of the lens. The eye still lies close upon the roof of the 

 thalamencephalon, and closely pressed against the " stalk " 

 behind. Its position is indicated by the letters Pa. E. in 

 fig. 98. 



The paraphysis is still a simple diverticulum of the front 

 part of the roof of the thalamencephalon, but it has begun to 

 be folded. 



Stage P (fig. 101). 



Of this stage I have only a single specimen, numbered 87, 

 collected on Stephens Island about the end of November, 1897, 

 and removed from the egg on January 25th, 1898. I suspect 

 that this embryo was already dead before the e^g was opened, 

 though apparently still in good condition. 



The foetal membranes were evidently somewhat injured, pre- 

 senting at the time when the drawing was made the arrange- 

 ment shown in fig. 101. 



The embryo has completely extricated itself from the yolk- 

 sac, and lies entirely above it on its left side, so that the pro- 

 amnion has ceased to exist. It remains attached to the yolk- 

 sac, however, by the now greatly elongated splanchnic stalk 

 (Sia.) containing the main trunks of the vitelline vessels. 

 The clear area of the yolk-sac around the embryo is in this 

 specimen still very extensive. The amnion (A77i.) has been 

 ruptured and shrunk away from the front part of the embryo, 

 still, however, partially enveloping the posterior part of the 

 body. Owing doubtless to the rupture and shrinkage of the 

 amnion, the junction between the latter and the serous enve- 

 lope (*S'. En.) has been pulled backwards instead of lying in its 

 normal position above the shoulders. Later on, at Stage R, 

 the true amnion was again found continuously enveloping the 

 entire embryo, so that its rupture and absence from the anterior 

 portion in this specimen is doubtless due to accident. 



