February 34, 1899.] 



ISCIENCE. 



281 



tributed among the caves throughout the 

 valley " (of the Mississippi). 



Two of the specimens from Missouri 

 served Kolil (Eudimentiire Wirbelthier- 

 augen, 1892) for his account of the eyes of 

 North American blind fishes. At my re- 

 quest Mr. Garman sent me two of the Mis- 

 souri specimens. He urged me at the same 

 time to make a more extensive comparison 

 between them and the Mammoth cave 

 specimens. A comparison of the eyes of 

 specimens from the two localities not only 

 proved that they represent distinct spe- 

 cies, but that they are of separate origin. 

 An announcement of the species without 

 further description was published (Proc. 

 Ind. Acad. Sci. for 1897, p. 231, 1898). The 

 species was " named rosm for the rediscov- 

 erer of the California TypJdogobms, a pio- 

 neer in the study of Biology among women, 



eight specimens. I have since received an 

 additional number from a correspondent. 

 From information gathered it would seem 

 that this species (or similar ones) has a 

 wide distribution in the subterranean waters 

 of the southern half of Missouri and north- 

 ern Arkansas, probably also the eastern 

 part of Kansas. 



On the surface the specimens very closely 

 resemble Typhlichthys subterraneus from 

 Mammoth cave, differing slightly in the 

 proportion and in the pectoral and caudal 

 fins. These fins are longer in rosce. It is, 

 however, quite evident from a study of their 

 eyes that we have to deal here with a case 

 of convergence of two very distinct forms. 

 They have converged because of the simil- 

 arity of their environment and especially 

 owing to the absence of those elements in 

 their environment that lead to external 



Fig. 1. Side view of Troghlichtys showing the extent and distribution of the tactile organs. 



Mrs. Eosa Smith Eigenmann." In the 

 spring of 1897 I visited various caves in 

 Missouri to secure additional material of 

 what was recognized as in many ways the 

 most interesting member of the North 

 American fauna. 'No specimens were se- 

 cured, but a liberal number of bottles of 

 alcohol and formalin were scattered over the 

 •country. During the fall of 1898, through a 

 grant from the Elizabeth Thompson Science 

 Fund and through the courtesy of the ofii- 

 cers of the Monon, the L. E. and St. L. 

 and the Frisco E. E. lines I was enabled 

 to visit the cave region of Missouri again. 

 This time I visited nine caves and secured 



protective adaptations. The details of the 

 structure of the eyes of all the members of 

 the Amblyopsidae will be published shortly, 

 and I heed call attention here only to the 

 structures that warrant the conclusion that 

 the cis- and trans-Mississippi forms of blind 

 fishes without ventral fins are of distinct 

 origin. The blind fish Amhlijopsis may be 

 left out of consideration, since it is the only 

 member of the family that possesses ven- 

 tral fins. Otherwise, it would be difficult 

 to distinguish specimens of similar size of 

 this species from either subterraneus or rosce. 

 The eye of T. subterraneus is surrounded 

 by a very thin layer of tissue representing 



