6 



CONARIO-HTPOPHTSIAL TRACT. 



that bone and the frontal, rarely the frontal bone itself, and 

 then near the suture, always opposite the interval between 

 the fore and mid brains. Beyond this hole, commonly called 

 "foramen parietale," but which may preferably be termed 

 foramen pineale," the upward continuation of the conario- 

 hypophysial tract or tube (fig. 1, 7,8) is closed by the scalp 

 or supracranial integument. 



Pig. 1. 



Section of cranium and brain of young Iguana^ showing foramen 

 parietale &c. — 1. Neural axis. 2. Vertebral column. 3. Cerebellum. 

 4. Optic lobe. 5. Thalamencephalon. 6. Cerebrum. 7. Pineal body. 



8. Pituitary body — conario-hypopbysial tract (including " infundibulum " 

 and " third ventricle ") ; 8' indicates the " protopharynx " of the embryo. 



9. Mouth. 10. Gullet. 



To the embryologist the so-called " pineal gland " first 

 manifests itself as a hollow pyramidal or papillary extension 

 of the roof of the large mid-cerebral vesicle, or " thalamen- 

 cephalon " (fig. 4, 5). In the cold-blooded Vertebrates it 

 inclines forward ; in Mammals and to some extent in Birds 

 it is directed backward. In all it seems in quest of an open 



Illustrated Catalogue of the Possil Reptilia of South Africa in the British 

 Museum," showing the parietal or " pineal " foramen in the genera Gale- 

 scmrus, Petrophryne, Dicynodon, Ptychognathiis, Oudenodon, KistecepJialus, 

 and Frocolo£ho)t : in some of tlicso genera the hole is unusually large. 



