1891.] Zoology. 487 
ZOOLOGY. 
Plathelminthes.—Dr. Braun in Bronn’s ‘‘ Klassen und Ordnungen 
des Thier-Reichs,’’ Bd. IV., catalogues the known species of ectopara- 
sitic Trematodes. The following species are enumerated from North 
America: These are Zristomum maculatum from Diodon sp. ; ? Plec- 
tanocotyle elliptica from Labrax mucronatus; Polystomum coronatum 
from Cistudo carolina; Pol. oblongum from Dromochelys odoratus ; 
and Sphyranura osleri from Necturus lateralis. As soon as our species 
are systematically studied this list will be greatly increased. 
Hermaphroditism in the Crustacea.—Dr. Ishikawa! describes 
the hermaphrodite glands in Gedia major. The anterior part of the 
reproductive organ is male, and the vasa deferentia are much as usual 
in Decapods. The posterior half of the organ is female, and is much 
larger than the rest. In sections the germinal band in the testicular 
portion is seen giving rise to spermatozoa, while in the ovarian part 
the same band forms eggs. At the point of junction eggs and sperma- 
tozoa are commingled. Grobben thinks that these eggs cannot escape 
through the narrow generative opening, and hence must atrophy at 
certain seasons of the year. This hermaphroditism was found to occur 
in all of twenty males examined. 
Observations on a Remarkable Development in the Mud- 
fish.—An interesting example of abnormal development may be seen 
in some mudfishes (Protopterus annectens), now in the Zoological 
Gardens of London. Eight rather young ones, of from six to eight 
inches long, were brought to England in the summer of 1889, and 
have ever since occupied one capacious tank. It was soon seen that 
they viciously snapped at each other, maiming and nipping off each 
other’s filamentary fins, then about two inches long, but which, how- 
ever, soon grew again. By degrees, and particularly within the last 
six months, I observed that, in consequence of frequent mutilation, 
the fins did not attain their normal length, but were stouter and flatter, 
less and less filiform, and with a more distinct fringe, as if nature were 
compensating in breadth what was lacking in length. The fish, being 
now much grown, snap at each other with greater force. The biggest 
is nearly two feet long. 
During our unusually severe winter my observations were suspended, 
‘and I was therefore greatly surprised in February to find that one of 
1 Zool. Anz., XIV., 70, 1891. 
