REPORT ON THE GREEN TURTLE. 29 



is the iufuudibulum (inf.), aud is seen to be quite separate from the lobes of the 

 racemose pituitary body {2^1/ ■): the upper part of wliich becomes the permanent engrafted 

 pouch. 



The notochord (nc.) is seen running up for some distance into the thin, median part 

 of the post-clinoid {p.cl.) ; there it is somewhat bent forward, and it is covered at its 

 fore end with' a sheath of thickening cartilage. This section being near the middle, 

 shows the distance between the investing mass and the " intertrabecular " bar. There is 

 here a membranous space below the pituitary body, not yet floored with cartilage. 



Only the lower part of the hind-brain (C 3) is figured, and this is shown running, 

 after it has formed its downward flexure, into the myelon {my.). The notochord is seen 

 to become larger as it enters the vertebral column. 



Horizontal Sections of the Head. 



In this series the head was sliced from above downwards ; by this means the fore 

 part was displayed in deeper and deeper regions in a regular manner, but, on account of 

 the mesocephalic flexure, the hind part of the head was cut across from side to side 

 almost at a right angle to its axis. 



First Section. — Part of the brain is shown in this section (PI. VIII. fig. 1). The fore- 

 brain is cut through where the " rhinencephala " (C 16) are budding out, and the 

 mid-brain (C 2) where it is passing into the hind-brain, behind the folded part. 



The recesses in wliich the olfactory lobes lie are the same as those which became 

 cribriform, first in cartilage and then in bone, in the Mammalian skull. The chondro- 

 cranium is cut through along its sphenoidal alae, the orbito-sphenoid passing directly into 

 the alisphenoids {o.s.,al.s.). Between these walls and the eyeball (e.) the upper orbital 

 muscles and nerves are seen. 



Second 'Section. — A little deeper down (PL VIII. fig. 2) the olfactory nerves are seen 

 giving ofi" branches to the nasal mucous membrane ; the orbito-sphenoidal cartilages {o.s.) 

 are converging below, and the alisphenoidal part {al.s) is here thin and wavy These 

 run into the top of the post-clinoid walls {p.cl.) at its sides ; this is cut through at its 

 top, and does not show the middle part. 



Third Section. — Here (PI. VIII. fig. 3) the nasal cavity is cut across, and the 

 olfactory nerves are seen to be highly subdivided as they, enter the cavity on each side. 



The septum nasi, and alae {s.n.,al.sp) are cut through, and the orbito-sphenoids {o.s.) 

 are seen to their base, where they arise from the lateral elements of the orbital septum 

 (trabeculse). The alisphenoids {al.s.) are in two parts at this level ; they bound the 

 recess into which the infundibulum grows to meet the pituitary body, and in the fore 

 part of which the optic nerves (2) pass out to the orbit, and their upper lobe is seen to 

 articulate with the post-clinoid wall {p.cl.) at its outer edges, as the front part of these 



