778 The American Naturalist. [September, 
either she or her ancestors must have had some idea of what was being 
accomplished. The point here seized upon and utilized in the devel- 
opment by natural selection is so different from those usually utilized. 
The points usually developed into permanent habits by natural selec- 
tion and inheritance are, commonly occurring, easily understood laws. 
I, however, surely believe with Riley and others that this perfect 
adaptation of Yucca and Pronuba must be the result of natural selec- 
tion, the gradual modification of some archetypal form. 
However this development took place, one watching Pronuba’s 
actions at the present time, so full of purpose and understanding, can 
hardly fail to conclude with Riley that it is not “ blind instinct” alone 
that guides her—H. J. WEBBER, Shaw School of Botany. 
ZOOLOGY. 
Trematodes.—All authors agree that Trematodes are provided 
with a superficial cuticle which is pierced by numerous minute canals, 
but their statements in regard to the origin of this cuticle are very 
contradictory. Thus Ziegler looks upon the cuticle as a metamor- 
phosed epithelium, Schneider and Minot consider it the basal mem- 
brane of an epithelium which has been lost in the parasitic life of the 
worm, while Leuckart describes it as a product of the subcuticula. 
To these three theories Dr. Brandes, of Halle, now adds a fourth! of 
which the following is a brief resumé: 
Trematodes do not possess any subcuticula in the true sense of the 
word ; the subcuticula described by Leuckart and others is parenchy- 
matic tissue which, together with a similar tissue found between the 
muscles, Brandes names ectoparenchym, to distinguish it from the 
endoparenchym, i. e., the parenchym in which the genital organs are 
imbedded ; there is, however, a true cuticle present, which is a product 
of the suboutiouler glands; the cuticle is not pierced by canals.—C. W. 
STILES. 
Fishes of Ohio.—Oberlin College has begun the publication of a 
“Laboratory Bulletin.” The second number, which has just 
appeared, contains a “ Descriptive list of the fishes of Lorain county, 
Ohio,” by the museum assistant, Lewis M. McCormick. In all 89 
species are enumerated, and Etheostoma wrighti is described as new. 
1G, Brandes, Zum feineren Bau der Trematoden, Zeitschrift f. w. Zool., 1892, Bd. 
liii, 4. 
