Geology and Natural History. 477 
The other differences are all very slight, scarcely suflicient to dis- 
tinguish the subterranean form as a species, and certainly so slight 
that they would almost surely be overlooked if the two forms 
As the crustaceans have recently been several times referred to 
as wren re the partially marine origin of the cave fauna of th 
rn States, a word in regard to their affinities may not be out 
e 
Crangonyx vitreus Smith, Mammoth Cave; C. Packardii Smith, 
wells, Ind.; Cacidotea stygia Packard caves and w ells, Ind., 
Asellus, a Se cae fresh water genus. The Z icwsa 
was found also o put side the caves sa is allied to other terrestrial 
genera e Cauloxenus, a Lernean parasite of the blind fish, 
18 80 poorty Jeunes and Sneey nasal the genera of the whole 
ich it belongs are so difficult and a ee i 
that it is useless to speculate on its exact affinities. In o 
Western and Southern States, species of perch, eg mes the 
siscowet, lake white-fish, species of Catostomus and s, and 
other fresh water fish » are — with different gus 
Lerneans, and there is no mo ason for regardin 
8 arine form” than any of te As might 
we call a Cambarus or a Crangonyx a marine form because the 
great majority of the ao of the orders to which they belong 
are marine. Considering the crustaceans alone, I can sec no 
reason for supposing that the taal of the caves of Kentucky and 
Indiana has been derived from any other source than the recent 
17. United States Commission of Fish and Fisheries. _ Part 
together with extended accounts of what has been aceomplis 
in the way of artificial ee of the fishes, and their intro- 
i i fe n all parts of the United States, 
lowing summary of contents :—Inquiry into the decrease of the 
food 4 shes; Action in regard to propagation of food-fishes (shad, 
* 
