Jordan and Evermann. — Fishes of North America. 705 



Concerning the distribution and habits of this fish, Mr. Garman gives 

 the following pertinent remarks : 



" TypJdichlhi/s suhterraneiis, Girard, tho ouly blindfish in the collection (of Miss Ruth Hoppin, 

 from caves in Jasper County, in southern Missouri) is represented by a large number of exam- 

 ples, the majority of them taken from tho wells, tho balance from tho caves, with tho exception 

 of a single one from the creek outside. Compared with specimens from Kentmky and Tennessee, 

 they agree so exactly as to raise the question whether the species was not originated in one of tho 

 localities and thence distributed to the others. The opinion generally held is that the cave 

 species of Indiana, Kentucky, and Tennessee originated in their respective localities. It is no 

 doubt true for some of them. The idea is well supported by tho insects and Crustacea, the 

 species in one section being unlike those of the others. It may be urged that the respect in 

 which the fishes differ from them is more apparent than real, since these Crustacea aud insects 

 were derived from a numlier of distinct species, while in all probability the same species of fish 

 entered the caves in each district, .and, being under the same influences in each, suffered tho 

 same modification in each. Reduced to its lowest terms the que.<tion, so far as the fishes are 

 concerned, is this: Were the blindfishes distributed to the scattered localities where now found 

 before or after they became blind ? In favor of independent origins at distant points, it can be 

 said that a species, distributed over the valley, possessed of habits such as would lead it to place 

 itself under the modifying conditions of the cave in one place, would be most 'likely led to do so 

 in the others. On the other hand, we have the more hesitation in accepting the conclusion that 

 one and the same species originated independently in two or more different localities, from know- 

 ing that exact parallels in the development of animals in nature, if they exist, are excessively 

 rare. If our caution prevents ready acceptance of two apparently exact evolutionary parallels 

 as really coincident, we become more skeptical when the number of parallels or coinciding lines 

 is increased. There is no doubt that the representatives of TyphUrlillii/ssHllen-aneus in tho various 

 caves were derived from a single common ancestral species. Tho doubts concern only the prob- 

 ability of the existence of three or more lines of development, in as many different locations, 

 starting from the same species and leading to such practical identity of result. Such identical 

 results would demand substantially similar modifying elements — darkness, temperature, food, 

 enemies, etc. — and the same length of time subjected to their influence. The likelihood of the 

 existence of so many like elements in distant regions is inversely to the number demanded, 

 though one can not say it is impossible. To accept the conclusion favoring independent devel- 

 opments of the same species would involve acceptance of the idea that the caves in each of the 

 districts had been occupied fur about the same period of time. This, of course, would not fur- 

 nish us with any clue to the time of formation of the caves. As an alternative, the opinion is 

 here advanced that these blindfishes originated in a particular locality, and have been, and are 

 being, distributed among the caves throughout the valley. 



"We are in the habit of looking upon great rivers like the Ohio or Mississippi as impassable 

 obstacles to passage from cave to cave, rather than as thoroughfares. In this we have certainly 

 assumed too much. Various instances are on record of the discovery of blindfishes that have 

 strayed into the open streams from their caverns. If there were means of determining the fre- 

 quency of the occurrence of such instances, it would undoubtedly much exceed what we are 

 now inclined to credit. Persons acquainted with the streams of the Mississippi basin will agree 

 that their undermined banks provide series of recesses or caverns, extending from the rills at the 

 sources to the tributaries and to the Gulf. The currents do not prove insurmountable to multi- 

 tudes of fishes, no better provided with locomotive organs than the blindfishes, passing up the 

 streams every season. Swept from the caves by the torrents in the flooded mouths, the blind 

 species would find itself protected at once from light or enemies by the turbid waters. The tempera- 

 ture of the water at such times is low, and, should the light penetrate so as to prove detrimental, 

 retreats exist on every hand in the excavations of the banks or the mud of the bottom. What 

 migrations these fishes may make in winter wo can only imagine. Hiding places are so numer- 

 ous and extensive as to suggest the possibility of the evolution of blind forms without thocaves. 

 The great essential would be the disposition to avoid the light, opportunities existing everywhere; 

 the surroundings then would bring the organization into harmony with their demands, sooner 

 or later, as the creature was more or less plastic and yielding; disuse of the sense of sight being 

 followed by its loss and atrophy of its special organ. Development of sightless forms in the 

 holes and burrows of tho banks, or in tho mud of the bottom of the river, would here follow a 

 similar course to that gone through at great depths in lake or ocean. 

 F. N. A. 46 



