ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
555 
Spawn and Embryos of Eledone.* — Herr Korschelt gives a de- 
scription of a mass of spawn of this Ceplialopod, which was taken at 
Rovigno in August. There were about 140 eggs in the mass, which was 
attached to a Pmwa-shell ; each egg is surrounded by a transparent 
envelope, which is produced into a stalk ; the eggs are of very large size 
compared with those of other Cephalopods, for without the stalk they 
measure 15 mm. This account does not agree with that of Joubin, but 
it is possible that the spawn of a different species of Eledone was 
exasnined by him. Herr Korschelt thinks his species was E. moschata. 
In more fully developed eggs, when the embryo was well advanced, the 
yolk-sac was found to be still of an extraordinarily large size. A more 
complete knowledge of the embryology of this Octopod would be of great 
interest. 
B. Pteropoda. 
Pteropods with Two Separate Sexual Orifices.| — Mr. H. McE. 
Knower finds from a study of Cavolinia longirostris that the text-book 
statement that Pteropods have only one external generative orifice is 
incorrect. The author appears to accept the current statement for all 
other Pteropods, as, after describing the arrangements which obtain in 
C. longirostris, he proceeds to say that in the possession of two separate 
sexual openings it differs from all other Pteropods; these latter he 
regards as representing the more primitive condition of the hermaphro- 
dite duct, while the species under discussion has become more specialized. 
y. Gastropoda. 
Laws of Cleavage in Limax.J — Mr. C. A. Kofoid begins his essay 
with explaining his terminology. The egg is spoken of as having its 
animal pole uppermost, and the terms right and left, upper and lower, 
are used as if by one resident in the egg itself. By a “ generation of 
cells ” is meant all those cells which are removed from the ovum by the 
same number of cell-divisions, regardless of the time of appearance or 
position of such cells. The cells cleave in sets of four throughout the 
spiral period of cleavage, and these sets of four related cells of co- 
ordinate origin are called quartets. The regions of the segmenting egg 
occupied by the first four blastomeres and their derivatives during the 
spiral period are called quadrants, and designated by the letters a, 6, c, d. 
In Nereis and Umbrella , these designate the left anterior, right anterior, 
right posterior, and left posterior quadrants respectively. By the term 
spiral is indicated “ the divergence immediately after cleavage of the 
centre of the nucleus of the upper one of two daughter-cells from the 
vertical plane passing through the corresponding portion of the lower 
cell and the vertical axis of the egg.” This divergence or apparent 
shifting of cells, in Limax at least, is the result of the obliquity of the 
plane of division, and is predetermined by the position of the spindle. 
It will be convenient to designate each cell of the spiral period of 
cleavage by three characters : (1) a letter, indicating the quadrant, 
e. g. a ; (2) a first exponent indicating the generation, e. g. a 4 ; (3) a 
second exponent indicating the quartet or story, e. g. a 4,1 . Mr. Kofoid’s 
* SB. Ges. Nat. Freunde Berlin, 1893 (1894) pp. 68-73 (2 figs.). 
f Johns Hopkins Univ. Circ., xiii. (1894) pp. 61 and 2. 
J Proc. Am. Acad., 1894, pp. 180-203 (2 pis.). 
