MUSEUM OF COMI'AIJATIVE ZOOLOGY. 95 



I have dwelt thus at length on this question of color in other blind 

 fishes because Eigenniann ('90, p. 68) has said with reference to the 

 color of Typhlogobius tliat " in its pink color and general appearance 

 this fish much resembles the blind fishes inhabiting the caves of South- 

 ern Indiana." I suppose this to x-efer to Amblyopsis, as there is not to 

 my knowledge any other blind fish known from the caves of this region. 

 Whether Eigenmann's statement about the color of the Indiana fishes 

 is to be taken as opposed to those quoted from other writers or not, the 

 most significant fact for our purpose is that there is certainly no such 

 degree of vascularity in the integument of Amblyopsis as is found in 

 Typhlogobius. I have had opportunity to examine a well preserved alco- 

 holic specimen of this species, obtained by Professor Mark from Professor 

 Putnam. I prepared fragments of the skin in the same way that had been 

 employed in studying that of Typhlogobius, and found the blood-vessels 

 here to be .even less abundant than in the integument of the Clevelandia 

 and Lepidogobius that I have examined. 



The most serious objection, I think, to the supposed respiratory func- 

 tion of the skin lies in the thickness and density of the epidermis, and 

 the fact that the entire surface is thickly beset with the slime-secreting 

 cells (see Figs. 9, 10, and 17). I do not believe, however, that the 

 epidermis here would offer greater resistance to the interchange of gases 

 tlian would that of the frog ; certainly, as regards the integumentary 

 glands and their products, the frog's skin can hardly be more favorably 

 constructed for a respiratory function than that of the blind fish. When 

 we remember the dense cuticular layer that covers the entire surface of 

 such animals as the earth-woim, where all the I'espiration must be carried 

 on through the body wall, this obstacle does not seem so great. More- 

 over, in Cobitis fossils, where intestinal respiration is well known to take 

 place to a considerable extent, although it was long supposed that no epi-- 

 thelium was present in the region of the intestine, — in which from the 

 richness of the blood-vessels the respiration is supposed to be carried 

 on, — Lorent has shown not only that there is an epithelium present, but 

 that it consists of two layers, a superficial layer of flat polyhedral cells, 

 and beneath this a layer of stratified cylindrical epithelial cells, among 

 which are scattered beaker cells (Wiedersheim, '86, p. 572). 



Of course the ultimate test of my theory must be made by physio- 

 logical experimentation, and I hope to be able to do this before long. I, 

 cannot suppose gill respiration to be to any great extent supplanted by 

 integumentary respiration, since the gills appear to be normally devel- 

 oped. It is necessary, then, to suppose that the latter method supple- 



