A BLIND SNAKE FROM CUBA. 263 







Passing between the limiting membranes are the radial sup- 

 porting Mullerian fibers. 



II. THE EYE OF TypJilops vennicnlaris. 



The work thus far on blind snakes has been done by Kohl on 

 Typhlops vermicularis, a species found in Greece and the south- 

 western part of. Asia, and on Typlilops braininns, a species found 

 in the islands of the Indian Ocean and in Africa south of the 

 equator, accounts of which are given in his " Rudimentare Wir- 

 belthieraugen." 



He found that in depth the eye of Typlilops vermicularis is 

 equal to about one sixth that of Tropidonotns. 



The brille is thicker in Typhlops than in Tropidonotns and, com- 

 pared with the axial diameter of the respective eyes, is seven 

 times thicker. In Typlilops the brille is equal in thickness to 

 about one half that of the ordinary skin of the head. In Tropi- 

 donotns it is equal to one fourth. 



The cornea of TypJilops measures .0052 mm., and compared 

 with the relative sizes of the eyes is equal to about one half that 

 of Tropidonotns, which measures .064 mm. 



The conjunctiva is thickened at the edge of the disc-shaped sac 

 and consists here of gland -cells, the fornix conjunctiva. 



The supporting membranes of the eyeball, choroid and sclera 

 are relatively equal to about one half those of Tropidonotns. 



Harder's gland in Typlilops is many times larger than the eye- 

 ball. 



The six muscles are present. 



The lens is elliptical, while that of Tropidonotns is almost glob- 

 ular. The ratio of the lens volume of Typlilops to the eye vol- 

 ume is i : 14.04, while in Tropidonotns it is I : 3.6. The lens epi- 

 thelium of the former is relatively six times greater than that of 

 Tropidonotns. 



The retina at the back of the eye of Typ/ilops, and the retina 

 of Tropidonotns bear the actual ratio of 8:13, while compared 

 with the eye axis in each case the Typhlops-r&tim. is four times 

 greater. The fovea centralis and area are absent. 



'Kohl, Dr. C. "Rudimentare Wirbelthieraugen," Erster Thiel, Heft. 13, 

 Bibliotheca Zoologica. Verlag von Theodor Fischer, 1892, Cassel. 



