THE MICROSCOPE. Bile 
no female Pinnotheres, penetrated so far beneath the mantle of 
the pearl mussel as to be unable to retreat, one thing is quite 
clear, namely that the Meleagrina entombed the intruder in a 
cyst of pearl from which the clever pearl-bottom maker alone 
liberated him.” The Pinnotheres of the oyster, or “ oyster crab,” 
is a well-known crustacean ; but this is probably the first known 
instance of one being thus entombed; the females constantly 
live in the shell of their host, the males being only occasional 
visitors.— The Independent. 
HuMAN sPERMATOZOA.—Mr. E. M. Nelson has recently de- 
scribed, in the Journal of the Quekett Club, his observations on the 
human spermatozoa, the head or spore of which he states has 
hitherto not been correctly figured, in ail the drawings that he 
has seen the ovoid form having been delineated but with the 
larger end turned toward the tail, whereas the smaller end should 
be in that position. The head or spore fits into a cup, the out- 
lines of which may be seen in both front and side views. This 
part does not appear to have been previously observed. At the 
bottom of the cup is an exceedingly variable part called the 
calyx, between which and the tail proper is the stem, and in the 
latter a structure that Mr. Nelson names the joint. On the spore 
he has observed a flagellum which he calls the filament, its pur- 
pose being to guide the spore into the micropyle, or the aperture 
into the ovum. The paper is accompanied by a plate. 
BOTANY: 
ALG PARASITIC ON THE StoTH.—Mdme. Weber van Bosse de- 
scribes Algze comprising three new species and two new genera, 
found as parasitic growths on the hairs of two genera of Tardi- 
grada. On the side exposed to the light the hairs of these sloths 
are completely covered, when living in their very moist atmos- 
phere, to the extent possibly of 150,000 to 200,000 individuals 
on a single hair. One of the species is green, and appears to 
constitute a new genus. It has two kinds of reproductive 
organs, large ovoid macrozoosporcs with four cilia, and small 
ovoid or angular microspores, on which no cilia were detected. 
The mode of reproduction could not be followed. The two 
other parasitic Algee are violet in color, and from a new genus 
named Cyanoderma.—Journal R. M. Soe. 
