240 



SCIENCE 



[Vol. XX. No. 508 



THE ORIGIN OF THE CAVE FAUNA. OF KENTUCKY, 

 WITH A DESCRIPTION OF A NEW BLIND BEETLE. 



BT H. G ARM AN. 



It is common in writings on the origin of the cave fauna of the 

 United Slates to assume that th^ recent formation of the caves of 

 Kentucky is evidence of a similar recent origin of the blind ani- 

 mals which inhabit them. The geological evidence appears con- 

 clusive that the caves of the Green River region, and those to the 

 northward in Indiana, were occupied during the Champlain 

 period with water, and that their present inhabitants (at least the 

 air-breathing species) must consequently have taken possession 

 after the caves were elevated and the water no longer com- 

 pletely filled them. There can be no disputing the grounds for 

 this belief; the geological evidence is all that could be desired for 

 proof of a recent origin of the caves themselves. But I must 

 beg leave to dissent from the conclusions which have been drawn 

 from this proof, as to the recent origin of the blind animals. 

 Conditions requisite to the development of eyeless animals are 

 present io most parts of the United States. It seems only re- 

 quired that a species have no use for eyes, irrespective of the 

 presence of light, and the eyes become reduced. Animals which 

 burrow in the soil everywhere show a tendency to loss of the or- 

 gans of vision. The moles, the worm-snakes (Carphophis), and 

 Canibanis bartoni are familiar examples. Parasitic species lose 

 their eyes, not in all cases because of a life in darkness, but 

 because as parasites no eyes are needed. Numerous burrowing 

 insects with poorly-developed eyes are known to occur over wide 

 extents of territory. Beetles which live almost as exclusively in 

 the dark as Adelops and Anophthalmus are not at all rare. Quite 

 a list of non-cavernicolous blind beetles is known. It is to species 

 such as these, already fitted for life in caves, that we should look, 

 it seems to me, as representing the ancestors of cave species; 

 certainly not to ordinary species with well-developed eyes. The 

 originals of the cave species of Kentucky were probably already 

 adjusted to a life in the earth before the caves were formed, and 

 it seems probable from some facts mentioned below that they 

 were not very different in character from the animals now living 

 in the caves. I cannot believe that there has been anything more 

 than a gradual assembling in the caves of animals adapted to a 

 life in such channels. In this view of the matter the transforma- 

 tion of eyed into eyeless species appears to have been much less 

 sudden and recent than has been supposed. 



To take a definite example: There appears to be no imperative 

 reason for assuming that the blind crustacean, Ccecidotea (Asellus) 

 stygia, originated in Mammoth Cave. It was first discovered in 

 caves it is true, but occurs widely distributed in the upper Missis- 

 sippi Valley, is found throughout Kentucky, and is known to occur 

 as far east a^ Pennsylvania. It is throughout its range a creature 

 of underground streams, and is nowhere more common than on 

 the prairies of Illinois (the last place in the country in which one 

 would expect to find a cave), where it ma3' be collected literally 

 by the hunlreds at the mouths of tile drains and in springs. In 

 Kentucky, also, it is not more abundant in the cave region than 

 elsewhere, being very frequently common under rocks in springs 

 and in streams flowing from them, even during its breeding sea- 

 son. It isi only natural that such a crustacean should have found 

 itself at home in Mammoth Cave when this cavern was ready for 

 its reception. 



The blind fishes, again, are not by any means «onflned to the 

 caves, but are widely distributed in underground waters through- 

 out the country. Aniblyopsis spelceus occurs in Indiana, Ken- 

 tucky, and probably also in Missouri and farther south. Typhlieh- 

 thys suhterramzus occurs in Misjoari, Kentucky, Tennessee, and 

 Alabama. Chologaster agassizii occurs in Kentucky and Tennessee. 

 C. pa/iilliferus occurs in a spring in southern Illinois. I have had 

 the pleasure of taking this species, and can say that the spring is 

 evidently the outlet of an underground stream, and sends away 

 a narrow but vigorous rill at all times of the year. O. cornutus 

 I have taken, with the help of my friend. Professor B. P. Colton, 

 in North and South Carolina, and can speak positively as to the 

 situation in which it occurs. Like its relatives it is a fish of 

 underground streams, and makes its appearanc; at times at their 



mouths. Still another species appears, according to Dr. Packard, 

 to have been observed in California. Here are widely scattered 

 fishes with the family characters of Amblyopsis, and so probably 

 closely resembling the eyed ancestors of the latter. They illus- 

 trate my point that there were in existence species possessing at 

 least some of the characters of the Mammoth Cave forms when, 

 the caves became habitable; for it will hardly be supposed that 

 all of these fishes originated in the caves of Kentucky and have 

 become scattered since the glacial period. They illustrate, also, 

 the point that hundreds of generations of a species may exist 

 under the same conditions of environment as Amblyopsis and 

 Typhlichthys, and yet not lose their eyes. Why then should 

 these latter have had their eyes all but obliterated in the course of 

 a few generations? 



The distribution in this country of blind beetles of the genus 

 Anophthalmus might at first thought appear to favor the idea 

 that Mammoth Cave is a centre from which our species have been 

 disseminated towards the East. Of our eight described species 

 four (possibly five with A. audax) live in the Mammoth Cave 

 region. Two others occur in Wyandotte Cave, only a shortdis- 

 tance away. The single species not thus far recorded from these 

 caves is A. pusio of Virginia and eastern Kentucky. It is to be 

 remembered, however, that the large caves of Kentucky and 

 Indiana have been much more thoroughly explored for cave ani- 

 mals than those of other parts of the country, and that their size 

 and accessibility to Man have had much to do with the frequency 

 with which they hive been visited by collectors. They are sim- 

 ply portions of the haunts of the subterranean species which are 

 opened up to us. One of the blind species (Anophthalmus tenuis) 

 of Wyandotte Cave has now been found in Luray Cave, Virginia, 

 a fact which gives us reason for believing that the Mammoth 

 Cave species are more widely distributed than our present knowl- 

 edge indicates. The large number of species (64) occurring in 

 Europe points to that continent as the habitat from which all 

 species of the genus have spread. If we accept this view of the 

 origin of the genus then, whether the American species were intro- 

 duced into this country before or after the Champlain period, it 

 follows that our species have been but little modified by residence 

 in Mammoth Cave, for if they had been we should find them de- 

 parting more widely than they do from their European allies. 

 They are in fact very closely related to Euroj)ean species. If we 

 transfer the question of the sudden appearance of Anophthalmus 

 to Europe, and claim still that the species are of post-glacial 

 origin, that the eyes were lost suddenly after the Champlain 

 period, we are met with the difficulty that here there is a grada- 

 tion in both the habits and structure of the species which shows 

 that the change may be and probably always has been gradual; 

 for there are in existence species -.which live under rocks and have 

 rudiments of external eyes. 



Another aspect of this question of a sudden transformation of 

 the species has recently been brought to my attention by some 

 observations I have been making on the habits of these beetles, 

 and particularly on a new species of Anophthalmus, of which a 

 description is appended. Isolation in caves has been urged as an 

 important factor in the development of those peculiarities by 

 which cave animals are marked. It is assumed that the cave 

 species are completely shut off from all relations with their out- 

 of-door allies at an early stage in their phylogenic history. 

 Nothing, it seems to me, can be farther from the truth. They 

 are not even now isolated by anything except their inability to 

 look out for themselves in the presence of their eyed enemies. 

 Coecidotea stygia is often found associated with Asellus communis, 

 the eyed species from which it is supposed to have been derived. 

 The cave cricket, Hadencecus subterraneus, while occurring in 

 the depths of caves, has always in my experience been found most 

 abundant at the openings, where the twilight prevailing probably 

 does not prevent the use of its well-developed eyes. It is fre- 

 quently associated in such situations with its near relatives of 

 the genus Ceuthophilus. Nor are the blind beetles confined to 

 parts of caves in which total darkness prevails. Probably 

 Anophthalmus tellkampfii is as completely adapted to a life in 

 darkness as any of our species, and I have not yet found this 

 species in the light ; but T have found it abundant in a cave where 



