EEPORT ON THE GREEN TURTLE. 23 



gland {pnl.) is cut through. Here the trabeculae (tr.) are rounded rods, like those 

 of the Snake, and they occupy very little of the sides of the intertrabecula {i.tr.) which 

 is jDyriform in section, its thick end being below. 



Thirteenth Section. — This section (PI. V. fig. 7) is at the point where the pre- 

 sphenoid passes into the prepituitary part of the basisphenoid ; here the trabecule {tr.) 

 are much larger, and more perfectly round in section. At a great height alcove, the 

 orbito-sphenoids (p.s.) are seen just where they pass into the lesser alisphenoids. 



The hemispheres (C la) are now ending behind ; and under them the thalam- 

 eucephalon (C 1) is beginning to give off a bud which becomes the " infundibulum" {inf.), 

 but the small body seen here below this part is part of one of the lobes of the pituitary 

 body {ptj.). 



Fourteenth Section. — (PL V. fig. 8) Here the mid-brain joins the fore-brain (C 2, 

 C l) directly above the fore part of the pituitary space. The infundibulum and 

 pituitary body {inf.,py.) are quite distinct, and closed towards each other ; this will be 

 seen better in the next section. The sinuous cartilaginous wall is here the alisphenoid 

 {al.s.), which is continuous below with the trabecula {tr.), and in front with the orbito- 

 sphenoid. Here the "intertrabecula" {i.tr.) is broader and shallower than the trabe- 

 culse, and lies on a somewhat lower plane, to finish the pituitary cup. 



The granular tract on each side which dips outwards, over the palatal skin, is the 

 beginning of the pterygoid bone {pg.) ; osteoblasts are now rapidly forming. On the 

 outer edge of each pterygoid there is the section of a cartilaginous rod ; it is fiattish, 

 and has its convex edge looking inwards and upwards ; this is the " epipterygoid " {e.pg.), 

 still continuous with the quadrate. 



■ A granular tract on each side shows where the jugal process of the maxillary will be ; 

 and below, on each side of Meckel's cartilage {mh.), a similar tract shows the beginning 

 of the dentary {cl.). In the root of the tongue a pair of cartilages is cut through, which 

 is the fore part of the larynx {Ix.). 



Fifteenth Section. — The back of the eyeball (e.) is cut through in this section (PI. 

 VI. fig. 1), and here the back part of the " thalamencephalon " (C 1) joins the broadest 

 part of the mid-brain (C 2). The principal lobe of the pituitary body {j^y-) is seen to 

 be closed above, open below, and alate ; the part of the fore-brain above it is where the 

 infundibulum {inf.) is beginning to bud off. The alisphenoidal walls of the chondro- 

 cranium {al.s.) are here very irregular, answering to the form of the organs both inside 

 and out. 



The terete trabeculae {tr.) are severed behind the median rod, so that there is 

 a membranous floor to the sella turcica at this part. The cartilaginous epipterygoid 

 and the young bone-cells of the pterygoid are seen also in this section {e.p)g.,pg.) ; and 

 below the mouth (m.) we get a section of the mandibles, hypo-hyals, cerato-hyals, basi- 

 hyal, and larynx {mk.,h.hy .,c.hy.,h.hy. ,lx.). 



