144 ARTHUR DENDY. 



groups. McKay figured it in Hinnlia (25, figs. 1 , 8) as far 

 back as 1888^ but described it only as an evagination in front 

 of the pineal eye, " very similar to the eye itself." 



Leydig — as I learn from a short paper by Eycleshymer 

 (11) — finds instead of a single vesicle a group of five, which 

 later came into such close relation with the "epiphysis" that 

 Spencer figured both as one structure. Eycleshymer himself 

 describes the paraphysis in Am bly stoma as a median out- 

 growth of the posterior portion of the roof of the prosen- 

 cephalon. Lateral diverticula appear at its distal end, but its 

 cavity becomes obliterated proximally in a manner analogous 

 to that which occurs in the " epiphysis." The two structures 

 in Urodela never come into close relation, as in Reptilia, but 

 remain widely separate. 



The development of the paraphysis in Sphenodon has 

 already been described in these pages, and appears to agree 

 closely with what takes place in Lacertilia. It gives rise to a 

 mass of convoluted tubules, lined by short columnar cells and 

 intermingled with blood-vessels, which lies beneath the parietal 

 eye and in front of the parietal stalk (figs. 15, 16). These 

 tubules undoubtedly form a part of what is usually recognised 

 as the '' pineal gland." 



It thus appears that ray observations with regard to the 

 paraphysis support the conclusions of Leydig already noticed. 

 Hoffmann also, according to Eitter (29), considers that the 

 paraphysis or " ependyma" in tlie grown animal "comes to 

 take a not inconsiderable part in the formation of the epi- 

 physis." There appears to be no reason whatever for regard- 

 ing it as a sense-organ, while its structure certainly suggests 

 a glandular function. In origin it is intimately connected 

 with the choroid plexus of the lateral ventricles, as I have 

 already shown. 



