180 W. BALDWIN SPENCER. 



posterior part (i. e. near the pineal stalk) the cone-shaped 

 elements seem to be absent, and their place to be taken by 

 large nucleated spindles (Co^), which, as it were, bend round 

 internally (fig. 5) and give off processes running directly into 

 the fibres of the stalk. 



Connection with the Brain. — It has hitherto been 

 stated by all writers that the distal part of the epiphysis 

 becomes separated from the proximal which forms the pineal 

 gland of the adult, and that the former comes to lie (as shown 

 by de Graaf in Anguis fragilis) external to the cranial cavity 

 in the parietal foramen. De Graaf ^ figures in Anguis the 

 eye as fitted closely into the parietal foramen encased by con- 

 nective tissue, but separated by a considerable interval from 

 *he proximal hollow epiphysial stalk from which in develop- 

 Mient it has been cut off. 



In Hatteria, as also in several other forms to be 

 described below, longitudinal vertical sections show 

 clearly that the highly developed eye is connected 

 with the epiphysis by a solid and well-marked stalk, 

 which may be called the pineal stalk. 



This runs in the median line backwards and slightly down- 

 wards ; it enters the eye at the posterior end, the walls of the 

 optic vesicle being here (fig. 2) drawn out somewhat back- 

 wards. The relationship of the elongated rods to the stalk 

 has been already described ; passing backwards from the eye 

 the stalk makes a decided bend upwards, then pierces the wall 

 of the eve capsule at its most posterior point and runs straight 

 back to the epiphysis ; its fibres enter the latter, being appa- 

 rently connected with the cells of the apex and the under 

 surface. The pineal stalk contains elements which have much 

 the appearance of those found at an early stage in the deve- 

 loping nerve of the paired eyes, that is, they much resemble 

 cells which are undergoing a process of elongation so as to 

 form long fibres (figs. 2 and 4) ; some having undergone 

 considerable elongation, others being yet spindle shaped. 



There can be little doubt that this median, azygos, nerve 

 1 PI. 4, figs. 31, 32, 33, and 34. 



