18 



CRUSTACEANS OF THE CAVE. 



Fig. 132. 



Csccidotea styyia (side view). 



Fig. 133. 



less rapidity, and become finally fixed and habitual. Prof. Hagen 

 has seen a female of Cambarus Bartonii from Mammoth Cave, 

 " with the eyes well developed," and a specimen was also found 

 by Mr. Cooke. Prof. Hagen remarks that " C. pellucidus is the 

 most aberrant species of the genus. The eyes are atrophied, 

 smaller at the base, conical, instead of cylindrical and elongated, 

 as in the other species. The cornea exists, but is small, circular, 

 and not faceted ; the optic fibres and the dark-colored pigments 

 surrounding them in all other spe- 

 cies are not developed." It seems 

 difficult for one to imagine that our 

 blind craw fish was created sud- 

 denly, without the intervention of 

 secondary laws, for there are the 

 eyes more perfect in the young than 

 the adult, thus pointing back to an- 

 cestors unlike the species now ex- 

 isting. We can now understand, 

 why embryologists are anxiously 

 studying the embryology of animals 

 to see what organs or characteristics 

 are inherited, and what originate de 

 novo, thus building up genealogies, 

 and forming almost a new depart- 

 ment of science : comparative em- 

 bryology in its truest and widest 

 sense. 



Of all the animals found in caves, 

 either in this country or Europe, 

 perhaps the most strange and unex- 

 pected is the little creature of which 

 we now speak. It is an Isopod crus- 

 tacean, of which the pill bugs or sow bugs arc examples. A true 

 species of pill bug ( Titanethes albus Schiodte) inhabits the caves of 

 Carniolia, and it is easy to believe that one of the numerous species 

 of this group may have become isolated in these caves and modi- 

 fied into its present form. So also with the blind Niphargus sty- 

 gius of Europe, allied to the fresh water Gammarus so abundant 

 in pools of fresh water. We can also imagine how a species of 

 Asellus, a fresh water Isopod, could represent the Idoteidse in our 



CiEcidotea stygia (dorsal view). 



