XII 



PHYLUM CHORDATA 



45 i 



stage when the deposition of the eggs takes place, and it is 

 only after a more or less prolonged period of incubation that 

 the young, fully formed in almost every respect, emerge 

 from the shell and shift for themselves. Many lizards, 



k 



8t 



FIG. 271. Section of the pineal eye of Hatteria punctata. g> blood-vessels; h, 

 cavity of the eye filled with fluid; k, capsule of connective tissue; /, lens; m, 

 molecular layer of the retina; r, retina; st, stalk of the pineal eye; x, cells in 

 the stalk. (From Wiedersheim, after Baldwin Spencer.) 



however, and a few snakes are viviparous, the ova being 

 developed in the interior of the oviduct, and the young 

 reaching the exterior in the completely formed condition. 



