6 THE BLIND FISHES OF MAMMOTH CAVE. 
to investigate, and I believe, it will be found in the end, that, so 
far from being accumulated by the sea, the drift of the lowlands 
of Patagonia has been worn away to its present extent by the 
continued encroachment of the ocean in the same manner as the 
northern shores of South America and of Brazil have been. 
THE BLIND FISHES OF THE MAMMOTH 
CAVE AND THEIR ALLIES.” 
BY F. W. PUTNAM. 
Tur blind fish of the Mammoth Cave has from its discovery 
been regarded with curiosity by all who have heard of its exis- 
tence, while anatomists and physiologists have considered it as one 
of those singular animals whose special anatomy must be studied 
in order to understand correctly facts that have been demonstrated ~ 
from other sources ; and, in these days of the Darwinian and devel- 
opment theories, the little blind fish is called forth to give its tes- 
timony, pro or con. 
Before touching upon this point, however, we must call attention 
to the structure of the fish and its allies, and to others that are 
either partially or totally blind. 
In the lancelet (Branchiostoma) and the hag (Myxine) the eye 
is described ‘‘as simple in form as that of a leach, consisting sim- 
ply of a skin follicle coated by a dark pigment, which receives the 
end of a nerve from the brain.” Such an eye speck as this struc- 
ture gives would only answer for the simple perception of light. In 
the young ț of the lampreys (Petromyzon) the eye is very small and 
*It was eami to put e -a in the last number of the NATURALIST i 
nection article on t and its insect and crustacean life, but the ae “a 
eri the pat made o peine to postpone it. e are therefore oblige 
refer the reader to the December number for further information of the fauna of Py 
cave and a + hört account of the cave itself. — Eps. 
on Pro £. m yman questions this structure. 
nET ; h f Amm ocætes, 
and it was not until 1856, when Prof. aes sorntveetae the fact of a br orphosis in 
he lampreys, that their true position wa ined. Prof. Miil hae piaptars ga 
. history of the common European species aa. veer that it is ar r four years 
attaining its perfect form. With this fact before us and with the early = zalh the 
My $ + + 
vinoids still unknown, ancel 
yet gti to be a larval form of the Myxinoids, notwithstanding that it is eaid t = ray 
hy should 
Bee oe ot ae 
oe | AE E EIA tN CaN Cee eR ee Mere RE 
PSS OT Pe eT ee RE eS Iw See 
