96 Trans. Acad. Sci. of St. Louis. 
margins, so that there is no palpebral fissure in this one section from 
the center under a high power it seems as if the union was not yet 
quite accomplished. The conjunctival sac is still quite large. To 
the right the corneal epithelium is seen in oblique section. 
Plate XXXII.—Fig. 18. Vertical section through the lids of an 
adult Typhlotriton a little beyond the open palpebral fissure. It shows 
that the union between the eyelids in this part is as yet only an 
epithelial one. To the right the corneal epithelium. Fig. 14. Section 
through the retina of a larva of Typhlotriton. To the left and upward 
sclerotic, in the lower angle part of the cartilage tissue found in the 
sclerotic. To the right in the retinal tissue the transverse section 
of a large, probably venous bloodvessel. No layer of nerve fibres 
can be made out on the inner (upward) surface of the retina. The 
ganglionic layer appears to consist of six or eight rows of cells. The 
white space separating the ganglionic layer (downward) from the 
broad nuclear layer is the inner plexiform layer. In this section the 
separation between the nuclear layer and its two outermost layers 
of cells is not so marked as in others, but the outer cells correspond- 
ing to rods and cones can be well seen. They appear as conical or oval 
bodies. The space between these layers and the pigment epithelium 
is filled with detritus containing many fuscin needles. 
Plate XXXIII. Figs. 15 and 16. Sections through the retina of 
adult eyes. They show that there is very little difference between the 
retina of my specimens from the: larval or the adult state. Really 
the only difference I can find is that the outermost layer (rods and 
cones) seems to consist in the main of oval cells. From these cells 
small processes may be seen in many places to reach into the space 
between retina and pigment epithelium, which I take to be the outer 
segments of the typhlotriton’s rods and cones, although most of them 
are evidently disintegrated and form the detritus which fills this space. 
Plate XXXIV. Fig. 17. Section through the retina of an adult 
eye. Fig.18. Shows a transverse section of an optic nerve not very far 
from the eyeball. The large black mass is the choroid cut at a tangent. 
The nerve which lies below it is accompanied by a large number of 
darkly pigmented cells and surrounded by muscular tissue. Below is 
the palate with its cylindrical epithelium. 
Issued October 12, 1910. 
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