263 
On the Empryoitocy of Limutus PotypHemus. By A. S%. 
PackaRD, JR., M.D. 
(Read before the American Association for the Advancement of Science, 
August, 1870.') 
Tue eggs on which the following observations were made 
were kindly sent me from New Jersey, by Rev. Samuel 
Lockwood, who has given an account of the mode of spawn- 
ing, and other habits, in the ‘ American Naturalist.’ They 
were laid on the 16th of May, but it was not until June 3rd 
that I was able to study them. The eggs measure ‘07 of an 
inch in diameter, and are green. In the ovary they are of 
various hues of pink and green just previous to being laid, 
the smaller ones being, as usual, white. ‘The yolk is dense, 
homogeneous, and the yolk granules, or cells, are very small, 
and only in certain specimens, owing to the thickness and 
opacity of the egg-shell, could they be detected. 
Not only in the eggs already laid, but in unfertilised ones 
taken from the ovary the yolk had shrunken slightly, leaving 
a clear space between it and the shell. Only one or two 
eggs were observed in process of segmentation. In one the 
yolk was subdivided into three masses of unequal size. In 
another the process of subdivision had become nearly com- 
pleted. 
In the next stage observed, the first indications of the 
embryo consisted of three minute, flattened, rounded tubercles, 
the two anterior placed side by side, with the third imme- 
diately behind them. The pair of tubercles probably repre- 
sent the first pair of limbs, and the third, single tubercle the 
abdomen. Seen in outline the whole embryo is raised above 
the surface of the yolk, being quite distinct from it, and of a 
paler hue. In more advanced eggs three pairs of rudimentary 
limbs were observed, the most anterior pair representing the 
first pair of limbs (false mandibles of Savigny), being much 
smaller than the others. The mouth opening is situated just 
behind them. In a succeeding stage the embryo forms an 
oval area, surrounded by a paler coloured areola, which is 
raised into a slight ridge. ‘This areola is destined to be the 
edge of the body, or line between the ventral and dorsal sides 
of the animal. There are six pairs of appendages, forming 
elongated tubercles, increasing in size from the head back- 
' Dr. Packard complains that he has been misrepresented in our paper 
on the subject of his present paper, and we gladly avail ourselves of his per- 
mission to publish the paper at length.—Eps. 
VOL. XI.—NEW SER, 8 
