JUL i? ib9a 



PARIETAL EYE AND ADJACENT ORGANS IN SPHENODON. Ill 



On the Development of the Parietal Eye and 

 Adjacent Organs in Sphenodon (Hatteria). 



By 



Arthur Deiidy, D.Sc, F.L,.S., 

 Professor of Biology in the Canterbury College, University of New Zealand. 



With Plates 11—13. 



Table of Contents. 



PAGE 



1. Intkoduction ...... Ill 



2. Systematic Account of Observations on Sphenodon punc- 



TATUS ...... 113 



3. Discussion of Results : 



(a) Structure of the Parietal Eye — Retina — Lens — supposed 



Arthropod Characters . . . .129 



{/j) The Nerve of the Parietal Eye . . . 131 



(c) Relations of the Parietal Eye to the Parietal Stalk . 132 



(d) Evidence of the Paired Origin of the Parietal Eye and Stalk 135 

 ((?) Relations between the Parietal Stalk, the Epiphysis, and the 



Brain . . . . .140 



(/) The Paraphysis . . . . .143 



(ff) The Epiphysis of Sphenodo u and Lacertilia . . 145 



{/i) The Accessory Vesicle .... 146 



4. General Conclusions ..... 147 



5. List of References ..... 148 



6. Description of Figures ..... 150 



1. Introduction. 



My attentioii was first directed to this investigation by ob- 

 serving a stage in the development of the parietal eye in an 

 Australian skink, in which the portion of the optic vesicle 

 behind the lens appears to consist of two very distinct layers, 



VOL. 42, PART 2. — NEW SERIES. H 



