1890.] Zoology. 1201 
organs,—and this in the epithelial cells, and not in the muscles as Bar- 
furth thought. It also occurs in less quantity in the other peritoneal 
cells. 
Teredos in Telegraph Cables.—At a recent meeting of the 
Zoological Society of London attention was called to the fact that 
Teredos caused no little trouble to the managers of submarine cables 
off the Brazilian coast. These molluscs penetrate between the sheath- 
ing wires when in the embryonic stage, and then bore into the tanned 
jute, and even scoop out pieces from the gutta-percha sheathing of the 
conductor. Faults made by these Teredos are very difficult to locate, 
as they leave no external sign. 
Scarcity of Oysters.—Owing to overdredging the oyster supply 
of the Chesapeake will be very small during the coming winter. The 
packing houses in Baltimore are finding it difficult to obtain supplies 
sufficient to keep them going at the rate of last winter. In 1888 and 
1889 it was not unusual for the canning houses to steam 50,000 bushels 
a day, but this year the supply is at least fifty per cent. less. It does 
not need much of a prophet to point out that if the present overdredg- 
ing be kept up for a few years longer the supply of Chesapeake oysters 
will be a thing of the past. 
Hermaphroditic Anlage in Insects.—A very interesting and 
important article on the hermaphroditic anlage of sexual glands in 
Phyllodromia (Blatta L.) germanica has recently been published by Herr 
R. Heymons in the Zoologischer Anzeiger, August, 1890. ‘The article 
contains only the most important results of Herr Heymons’s investi- 
gations, which are to be published later in full. The investigations 
were carried on in the Berlin Zoological Institute, under the direction 
of Prof. F. E. Schulze, of Spongia fame. 
Herr Heymons undertook to work out as carefully as possible the 
development of the sexual glands ; and in the present incomplete state 
of our knowledge as to the origin and growth of these glands in in- 
-sects such extended study with the aid of modern technic is very wel- 
come. ‘The first appearance of the sexual glands is of particular in- 
terest. Herr Heymons observed that the sexual cells have their origin 
chiefly in the walls of the ccelomic sacs. A smaller portion arises 
from the unsegmented mesoblastic layer, at a period before the primi- 
tive segments make their appearance. The author is undoubtedly cor- 
rect in regarding this origin of the sexual cells from the walls of the 
body-cavity as an extremely primitive relation. It is interesting to note 
the correspondence with lower forms. In the Annelids, e. g., the genital 
