486 



NA TURE 



{April 1 8, 1872 



Assuming, on the principles of evolution, that the cave 

 animals were derived from other species changed by 

 migration from the outer world to the new and strange 

 regions of total darkness, it seems evident that geologi- 

 cally speaking, the species were suddenly formed, though 

 the changes may not have been wrought until after several 

 thousand generations. According to the doctrine of natural 

 selection, by which animal species pass from one into 

 another by a great number of minute variations, this time 

 was not sufficient for the production of even a species, to 

 say nothing of a genus. But the comparatively sudden 

 creation of these cave animals affords, it seems to us, a 

 very strong argument for the theory of Cope and Hyatt, of 



ri. i^-Camlr.i, ,!■:/; limn/ ,-. 



creation by acceleration and retardation. The strongly 

 marked characters which separate these animals from 

 their allies in the sunlight, are just those fitting them for 

 their cave life, and those which we would imagine would 

 be the first to be acquired by them on being removed 

 from their normal habitat. 



On introducing the wingless locust, Cciithophilns macn- 

 lattis into a cave, where it must live, not under stones, but 

 by clinging to the walls, its legs would tend to grow longer, 

 its antennas and palpi would elongate and become more 

 delicate organs of hearing as well as touch,* and the body 

 would bleach partially out, as we find to be the case in 



* After writing this article, and without the knowledge of his views, we 

 turned to Darwin's " Origin of Species " to learn what he had to say on the 

 origin of cave animals. He attributes their loss of sight to disuse, and re- 

 marks : — ' ' By the time an animal has reached, after numberless generations, 

 the deepest recesses, disuse will on this view have more or less perfectly ob- 



Hadena-cus subtcrranetus and sty^^iiis. The Carabid beetle, 

 Anopthalmus, extending farther into the cave, would lose 

 its wings (all cave insects e.xcept the Diptera have no 

 wings, elytra excepted) and eyes, but as nearly all the 

 family are retiring in their habits, the species hiding under 

 stones, its form would not undergo further striking modi- 

 fication. So with the blind Campodca, which does not 

 differ from its blind congeners which live more or less in 

 the twilight, except in its antennx- becoming longer. The 

 blind Adelops, but with rudiments of eyes, does not greatly 

 depart in habits from Catops, while on the other hand the 

 remarkable Stagobius of the lllyrian caves, which according 

 to Schiodte spends its life in crawling ten to twenty feet 

 above the' floors over the columns formed by the stalactites 



to which unique mode of life it is throughout perfectly 

 adapted, is remarkably different from other .Silphids. Its 

 legs are very long and inserted far apart (the prothorax 

 being remarkably long), with surprisingly long claws, while 

 the antenna;, again, are of great length and densely clothed 

 with hairs, making them most delicate sense organs." So 

 also are the limbs of the false scorpion, and the spider and 

 pill bug (Titanethes) of remarkable length. 



But the modifications in the body of the Spirostrephon 

 are such that many might deem its aberrant characters as 

 of generic importance. It loses its eyes, which its nearest 

 allies in other, but smaller, caves possess, and instead 

 gains in the delicate hairs on its back, which evidently 

 form tactile organs of great delicacy ; the feet are remark- 



hterated its eyes, and natural selection will often have effected other changes, 

 such as an increase in the length of the antenna; or palpi, as a compensation 

 for blindness." (5th Amer Edit, p. 143.) We are glad to find our views as to 

 the increase in the length of the antennae and palpi compensati.ig for the loss 

 of eyesight, confirmed by Mr. Dar^vin. 



* Schiodte remarks that * it is difficult to understand the mode of life of 

 Stngolnus troglodytes, or how this slow and defenceless animal can escape 

 being devoured by the rapid, piratical Arachnidans, or find adequate support 

 on columns, for inhabiting which it is so manifestly constructed. We are led 

 in this respect to consider the antenna;. Whatever significance we attach to 

 those enigmatical organs, we must admit that they are organs of sense, in 

 which view an animal having them so much developed as Stagobins, must 

 possess a great advantage over its enemies, if these be only Arachnidans. Its 

 cautious and slow progress, and its timid reconnoitring demeanour, fully in- 

 dicate that it is conscious of life being in perpetual danger, and that it endea- 

 vours to the utmost to avoid that danger. Darkness, which always favours 

 the pursued more than the pursuer, comes to its aid, especially on 

 excavated surface of the columns," 



