1884.] Zoology. 87 
The remainder of the paper is devoted to histological facts and 
an attempt to show the relations of the sponge structure to its 
parasitic mode of life. 
POLYMORPHISM AND PARTHENOGENESIS IN MitEs.—A. Berlese 
States that the adult Gamasus, like all parthenogenetic forms, 
produces viviparously hexapod nymphs, which never develop 
ova till they reach the mother-stage. Both the larvae and the 
nymphs are distinguishable by their soft hyaline epidermis and 
the complete absence of any reproductive organs, There are 
nymphs which ought to become males, and others which should 
become females; and this, which is the most frequent arrange- 
ment, may be spoken of as the normal series. In addition there 
are individuals which cannot be produced by the adults or the 
higher forms of the series, but they are derived from two distinct 
groups, which, like the adults, are of the ordinary, or of the 
extraordinary series. Thus G. tardus produces a special larva 
from which, by rapid metamorphosis, there is developed a larger 
Octopod nymph, During the whole of its development this form 
IS octopod and asexual; it molts as it grows, but does not seri- 
ously alter in form; at the later molts a slight difference may be 
detected between the future males and females, but there are no 
traces of any secondary sexual characters. 
A detailed account is given of the metamorphosis of G. tardus, 
G. coleoptratorum, G. stabularis and Trach ynotus inermis; in the 
last of these pzedogenesis is especially weil marked.— Fournal of 
Roy. Micr. Soc., April. 
WATER-COLLECTING APPARATUS FOR Mires.—Mr. C. F. George 
States that he has used the following in searching for Hydrachni- 
æ, and has found no other piece of apparatus so efficient: 
piece of thick brass wire is bent at about six inches from one 
€nd into a ring four or five inches in diameter. After connecting 
with some finer wire the two extremities of the ring, bend the 
Stout wire at right angles to the ring, and continue it for about 
four inches. Then make another ring about one and a half inches 
in diameter, and there terminate the wire, leaving the small ring, 
however, not quite complete. The two rings will thus be parallel — 
to each other. On the upper ring stitch a piece of tape, and to 
S sew a piece of muslin, made in the shape of a conical bag, 
and having its wider end affixed to the tape. Into the lower 
pening of this bag a small, wide-mouthed glass bottle, of about 
9 ounces capacity, should be fastened by a piece of thread or 
fine String, and the lower ring is then sprung around the neck of 
the bottle. The other end of the brass wire, which was left pro- 
J€cting for about six inches, is now to be firmly lashed to a light 
ane or stick, and the apparatus is complete. In order to use the 
@pparatus, move it gently backwards and forwards on the surface 
y the water , under the surface, or just above the bottom of the 
