98 BULLETIN OF THE 



The Integumentary Sense Papillce. 



1. These have been considered only so far as pertains to the question 

 ■whether they have been developed to compensate the rudimentary con- 

 dition of the eyes ; and it is concluded that such is not the case. 



2. The facts that lead to this conclusion are the presence in several 

 closely related genera — four at least — of the tactile papillse with the 

 same distribution as those of Typhlogobius, and in addition to this, on 

 parts of the body where they are not found at all in Typhlogobius, ex- 

 cepting in the smallest specimens ; and that the papillae that are present 

 in Typhlogobius are not more highly developed than those of correspond- 

 ing regions in related genera. 



3. In comparing the several species of blind fishes with a view to de- 

 termining under what conditions the tactile sense does become developed 

 to compensate the loss of sight, it is concluded that, while the greater 

 activity of the cave blind fishes might explain their more highly developed 

 tactile papillae, this cannot be afl&rmed as a general law, since other 

 blind fishes (as some at least of the deep-sea forms and probably also 

 the blind Silurids) ,are without tactile papillae, while we have no rea- 

 son to suppose them less active than the cave fishes. It is necessary to 

 have more knowledge than is yet possessed of the mode of life of the 

 various blind forms before this question can be fully answered. 



The Integiiment. 



1 . This structure has been studied with refei'ence to the pigment con- 

 tained in it, and the pink color of the living fishes. 



2. Very nearly if not fully as much pigment is present in the largest 

 as in the smallest specimens, the lighter color of the former being due 

 to the obscuration of the pigment by a thickening of the sub-epidermal 

 tissue between the pigment and the epidermis. 



3. The pink color of the living animals is due, in great part at least, 

 to a highly abnormal development of blood-vessels in the sub-epidermal 

 portion of the integument. 



4. So far as it has been possible to determine, this vascularity of the 

 skin is unique in this fish. 



5. The most probable explanation found of this condition is that it is 

 for the purpose of cutaneous respiration. 



University of California, Berkeley, 

 July 4, 1892. 



