80 BULLETIN OF THE 
throngh a long course of evolution, would furnish an excellent test of 
this belief. The eye here studied throws very little light on the question, 
however, — scarcely as much as does that of other known functionless 
eyes. But when we consider together the facts presented by the eyes of 
Myxine, Typhlogobius, Proteus, and Talpa, and possibly also Ambly- 
opsis and Gronias, this much seems quite certain: that the lens disap- 
pears before the retina; and that, where degeneration takes place at all 
in ontogeny, the lens is affected first and most profoundly, as seen in 
Proteus, and probably also exceptionally in Typhlogobius. Supposing 
the somewhat doubtful instance of a degenerating retina presented by 
the eye shown in Figure 19 to be genuine, we still have reason to be- 
lieve that its degeneration has been preceded by that of the lens, since 
the latter body is undoubtedly absent in this specimen, There can 
scarcely be a doubt, from physiological reasons, that the retina is consid- 
erably older, phylogenetically, than the lens, even though it can hardly 
be said to be so ontogenetically. 
Tun INTEGUMENTARY SENSE ORGANS. 
At present I treat this subject no further than pertains to the question 
whether the loss of sight in Typhlogobius has been compensated by 
an unusual development of the sense of touch, leaving the consideration 
of any morphological significance that the sense papillae may have with 
the hope that they may be studied developmentally at some future 
time. 
From the testimony of numerous writers, there is no doubt that 
compensations for such loss by the super-development of the other spe- 
cial senses, hearing, smell, and touch, are common among animals 
both invertebrate and vertebrate. For a discussion of this subject see 
’ackard (86, pp. 123-130). 
My conclusion with reference to the tactile sense in Typhlogobius 
is, that in all probability it not only has not increased, but has actu- 
ally diminished par; passu with the diminution of the power of sight. 
at least four — 
The reasons for this conclusion are that several 
genera of the Gobiide closely related to Typhlogobius are as well 
provided with tactile papille as is the blind fish, these organs being 
considerably more numerous and more widely distributed on different 
parts of the body in the other fishes than in Typhlogobius. The 
genera to which I refer are Gobius, Gobiodon, Lepidogobius, and Cleve- 
landia. The last two I have examined mysclf. The arrangement and 
