264 EFFA FUNK MUHSE. 



The fiber layer has its greatest thickness near the exit of the 

 nerve and gradually becomes thinner until, near the iris, scarcely 

 a fiber is found. 



The globular ganglion cells are arranged in a single layer ex- 

 cept occasionally for short distances, when they lie in a double row. 



The inner nuclear layer seems to be subdivided into four layers. 



There are no twin cones. Each cone consists of a cone cell, 

 stalk, middle and end members. The cone nuclei lie in two 

 series, but the stalks vary in length so that the distal ends of the 

 cone members reach nearly the same level. 



III. THE EYE OF TypJilops lumbricalis. 



The eye shows through the large ocular scale, which entirely 

 covers it. It appears as a black spot surrounded by an unpig- 

 mented circle. The preocular, also a large scale, overlaps the 

 ocular and reaches just to the edge of the eye (Figs. I and 2). 



General Account of the Eye. 



Compared with one of the garter snakes and in proportion to 

 the size of the head, the eye of Typhhps lumbricalis is located 

 further from the surface and occupies far less space, while Har- 

 der's gland, associated with the eye in both, is relatively much 

 larger in TypJilops. In a specimen of TypJilops lumbricalis 2 \ 

 cm. in length, the eye measured .306 mm. in width, and .387 

 mm. in depth. The greatest width of the gland of the same was 

 .711 mm. and the length was 1.067 mm. The gland completely 

 surrounds the eye up to the edges of the conjunctival sac (Figs. 

 3 and 4). In proportion to the size of the eyes, the gland of a 

 garter snake is much smaller than that of Typhlops lumbricalis, 

 but compared with RJdnenra floridaua J the gland of TypJilops 

 Iwnbricalis is but little more than half as large. 



The eye is covered by layers of epidermis and dermis, that 

 differ from these same layers on neighboring parts by being 

 thinner, more compact and free from pigment and glands. The 

 ocular scale, however, which covers the eye region, does not 

 differ in thickness from the other scales of the head (Fig. 3). 



1 Eigenmann, C. A., "The Eyes of RJnneura fton'dana," Proceedings of the 

 Washington Academy of Sciences, Vol. IV., pp. 533-548, Sept. 30, 1902. 



