ORIGIN OF CAVE LIFE. 27 



Schiodte spends its life in crawling ten to twenty feet above the 

 floor -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 antennae, again, are of great length and 

 densely clothed with hairs, making them most delicate sense or- 

 gans.* So also are the limbs of the false scorpion, and the spi- 

 der 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 impor- 

 tance. 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 remarkably long, as also the antennae. These are not 

 new formations but simply modifications, apparently by use or dis- 

 use, of organs present in the other species. The aberrant myrio- 

 pod and Stagobius are paralleled by the blind fish, an animal so 

 difficult to classify, and so evidently adapted for its abode in end- 

 less darkness. And as an additional proof of the view here taken 

 that these cave animals are modified from more or less allied spe- 

 cies existing outside of the caves, we have the case of the craw 

 fish, whose eyes (like those of the mole), are larger in the young 

 than adult, indicating its descent from a species endowed with the 

 faculty of sight, while in the adult the appendages are modified as 

 tactile organs so as to make up for its loss of eyesight, in order 

 that it may still take its prey. 



We thus see that these cave animals are modified in various 

 w^iys, some being blind, others very hairy, others with long ap- 

 pendages. All are not modified in the same way in homologous 

 organs ; another argument in proof of their descent from ancestors 



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

 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 anten- 

 na?. Whatever signilicauce 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 

 Stagobius, must possess a great advantage over its enemies, if these be only Arachni- 

 dans. Its cautious and slow progress, and its timid reconnoitring demeanor, fully 

 indicate that it is conscious of life being in perpetual danger, and that it endeavors to 

 the utmost to avoid that danger. Darkness, which always favors the pursued more 

 than the pursuer, comes to its aid, especially on the uneven excavated surface of the 

 columns." 



