MUSEUM OF COMI'AKATIVK /0OL0(JY. 75 



On the whole, it appears that the eye of Proteus is more rudimentary 

 than that of either Typhlogobius or Talpa. The most distinct indica- 

 tion of this is in the absence of the lens in the adult animal. 



Witii reference to it Schlanipp says ('92, p. 555) : " Die Linse [in Pro- 

 teus] wird gleichzeitig niit der Kinstiilpung der primiiren Augenltlase 

 angelegt, wjichst in den sekundiiren Augeubecher hiuein, wo sie bei der 

 Larve noch in der Gcgend des vorderen Augenpoles zu finden ist. Sie 

 koinnit aber iiber die zellige Struktur der embryonalen Linse nicht 

 hiuaus, erleidet vielmehr durch Niclitgebrauch alsbald eine RUckbil- 

 dung, so dass sic bei ganz jungen Thieren an Grosse und Zellmasse 

 schon bedeutend rediicirt ist, im spiiteren Leben aber resorbirt wird und 

 spurlos verscliwindet." 



The lens is present in Talpa, though it retains its embryonic cellular 

 structure throughout life, wholly according to Hess ('89, p. 8), partly 

 at least accoi'ding to Kohl ('89, p. 385) and otiiers. In this regard, then, 

 it is more rudimentary than the lens of Typhlogobius. The choroid 

 is present in Proteus, consisting, according to Kohl ('89, p. 40G) " aus 

 niehrereu Zellenlagen mit reichlichem Pigment, das sich stets in zwei 

 Lagen anordnet, von denen bald die eine, bald die andere die grossere 

 Stiirke besitzt. Die innere derselben reprasentirt das vielfach (so auch 

 Hess) schon zur Retina gerechneto Pigmentepithcl." It also contains 

 blood capillaries according to both Kohl and Hess. As regards the 

 choroid and the pigment lamella of the retina, it would seem, according 

 to those statements, that the eye of Typhlogobius, with its exceedingly 

 rudimentary choroid and greatly thickened pigment lamella, is some- 

 what more rudimentary — it may be even degenerate — than that of 

 Proteus ; though it must be borne in mind that the choroid is compara- 

 tively feebly developed in normal teleostean eyes. 



In Talpa the. choroid reaches a relatively slight development, and has 

 little pigment, while the pigment layer of the retina is highly developed 

 (Hess, '89, pp. .3 and 4). In this regard it more nearly agrees with 

 Typhlogobius than does Proteus. The iris, considerably thickened with 

 pigment, the ligamentum pectinatum, ciliary body, and ciliary muscle, are 

 all present, though reduced, in Talpa, according to Hess. 



With regard to the retina of Proteus, Schlampp's statement in his 

 summary is as follows : " Die Retina breitet sich, Mangels des central 

 Glaskorperraumes, nicht fliichenhaft aus, sondern wird eine solide 

 Kugel, welche axial von Sehnerven din'chzogen wird. In ihrem histolo- 

 gischen Bane weicht sie nicht wesentlich von der Netzhaut der Am- 

 phibien ab, die Endapparate erreichen aber die endgiiltige Form nicht." 



