MUSEUM OF COMPARATIVE ZOOLOGY. 87 



developed on the head and sides of the body of both Amblyopsis and 

 yyplilichthys. According to Packard ('8G, p. 127), Tellkampf regarded 

 these papillse " as without doubt increasing the tactile sense." I have 

 not seen this paper of Tellkanipfs, and do not know whether his mean- 

 ing would be that the tactile sense is increased as compared with what 

 it was in the same species before it was deprived of sight, or merely 

 that it is great as compared with other bony fishes. Leydig also be- 

 lieves that the tactile organs perform such a compensatory office ('83; 

 see also Wright, '84, p. 272). Packard ('86, pp. 127, 128) gives ex- 

 tracts from several letters of Dr. John Sloan that are interesting in 

 this connection. Although the writer does not expressly state his belief 

 that tlie sense of touch has been highly developed for the purpose of 

 compensating the lack of sight, he still gives very convincing evidence 

 of its extreme acuteness from personal observation on the fishes in their 

 native siuToundings. It should also be noticed that he specially tested 

 their powers of hearing and the effect of light upon them, and to both 

 he says they " manifested total indifference." Sloan's observations were 

 on Amblyopsis. Wyman ('72, p. 19) has described the ear of this spe- 

 cies as being "largely developed" in all its parts, and Cope ('72, p. 410) 

 found the sense of hearing " evidently very acute." As to the ques- 

 tion whether the sense papillae in Amblyopsis and Typhlichthys are in 

 reality developed as a compensation for the loss of sight, the testimony 

 furnished by Chologaster is of the greatest importance. Although this 

 genus was discovered and named by L. Agassiz in 1843, its characters 

 were best made known by Putnam. He ('72, pp. 22, 23) says : " In the 

 genus Chologaster we have all the family characters as well expressed 

 as in the blind species, though it differs from Amblyopsis and Typhlich- 

 thys by the presence of eyes, and the absence of papillary ridges on 

 the head and body, and by the longer intestine and double the number 

 of pyloric appendages, as well as by the position of the ovary." 



In 1881, S. A. Forbes ('82, p. 3) discovered a fish in Southern Illinois 

 which he identified as belonging to the genus Chologaster, but repre- 

 senting a new species. With reference to the point that vve are now 

 considering, the author writes : " The most important and interesting 

 peculiarity of this species indicates a more advanced stage of adap- 

 tation to a subterranean life than that of its congeners. On all the 

 surfaces of the head appear short rows of peculiar tubercles. . . . 

 When thus exposed [by being freed from the adjacent epidermis], they 

 closely resemble the papillae of Amblyopsis in form and size, and are 

 similarly oipped at the tip." Again (p. 5) he says: "The extraor- 



