18 
CRUSTACEANS OF THE CAVE. 
less rapidity, and become finally fixed and habitual. Prof. Hagen 
has seen a female of Camharus Bartonii from Mammoth Cave, 
“ with the eyes well developed,” and a specimen was also found 
hy Mr. Cooke. Prof. Hagen remarks that “ O. pellucidus is the 
most aberrant species of the genus. The eyes are atrophied, 
smaller at the base, conical, instead of cjdindrical 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 
FiA’. 132. 
Ceecidotea sti/gia (side view). 
Fig. 133. 
blind craw fish was created sud- 
denly, without the intervention of 
secondary laws, for there are the 
eyes more pey'fect 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 
w'e now speak. It is an Isopod crus- 
tacean, of which the pill bugs or sow bugs are 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 Idoteidae in our 
Cpecidotea stygia (dorsal view). 
