388 Coe and Kunkel— California Limbless Lizard. 
characterized especially by its strong ventral flexure and the relative 
straightness of the ventral side in a transverse section. 
From a superficial examination of the brain without the use of 
sections, the anatomy of the thalamencephalon cannot be ascertained 
at all because of the blood vessels and the large amount of connective 
tissue which form a thick sheath about the organ on the dorsal side. 
A large blood vessel (pl. x11, fig..1, 6.7) is often found leading from 
beneath the anterior end of the pineal body to the region of the 
pineal eye, which resembles very closely the pineal stalk or nerve as 
figured by Spencer (’86 ) in several instances. Sections have proven 
beyond a doubt that in the late embryos and adults of Annzella this 
“stalk” is simply a blood vessel. In other specimens in which this 
vessel was not distended with blood it was scarcely noticeable. 
Thalamencephaton. 
Although several facts of more or less interest have been noted in 
this region of the brain of Anniella, which have not been described 
for any other lizard, the pineal body is very similar to that of the 
closely related Anguis which has been carefully described by Fran- 
cotte (?96), Béraneck (’87), and others. 
Sagittal sections of the head of a number of very late embryos 
from 45 to 70™™ in length and of several adult individuals have fur- 
nished the material for studying with some degree of accuracy the 
anatomy of this part of the brain. The thalamencephalon is very 
much compressed laterally and the third ventricle is a rather narrow 
cleft extending dorso-ventrally between the optic thalami. The 
lateral walls of this region are in the form of a pair of more or less 
ovoid masses of nervous tissue with their long axes nearly horizontal. 
These two masses, the ganglia habenule, or optic thalami, form 
protuberances dorsally jast beneath the posterior ends of the cerebral 
hemispheres. The superior and posterior commissures in the embryos 
at hand are placed very close together, being separated by a very 
inconspicuous mass of cells apparently similar to the ordinary molec- 
ular cells of the adjacent parts of the brain. The posterior is some- 
what the thicker of the two and is situated ventrally and posteriorly 
with respect to the other. Both lie in the dorsal and posterior part 
of the lateral wall of the thalamencephalon. The roof of the third 
ventricle is non-nervous in nature; a single layer of cells similar 
in general appearance to the ependyma forms an irregular much sac- 
culated covering, the post velar arch of Minot (:O1), or the ‘ Zirbel- 
polster” (pl. xivu, fig. 47, e’) and the paraphysis (py). Both 
