XCVIII REPORT OF COMMISSIONER OF' FISH AND FISHERIES. 
appendages on the lower side of the abdomen or u tail.” The eggs are 
hardy, comparatively large, about one-twelfth of an inch in diameter, 
and each lobster carries at a time from 0,000 to 30,000, dependent partly 
upon its size. The circulation of water among them is maintained by 
the natural movements of the swimmerets, which indicate, in a meas- 
ure, the amount of motion to be given them in the hatching apparatus. 
As the attaching threads do not constitute an organic connection be- 
tween the eggs and the body of the lobster, they may be cut without 
causing injury to the former or suffering to the latter, and the eggs may be 
removed rapidly by means of scissors or a sharp knife. They are heavy 
and the McDonald automatic hatching jar is well adapted to their in- 
cubation, although the cod apparatus has also been successfully used 
for the same purpose. 
In the spring of 1886 the experiments were renewed by Capt. H. O. 
Chester and Prof. John A. Ryder, and were carried to a successful issue, 
being vigorously prosecuted during the entire Hatching season. Prof. 
Ryder also made a careful preliminary study of the development of 
the young,* and attempted the rearing of the embryos in confinement. 
When first hatched the embryo lobster is totally unlike the parent, 
both in shape and in the character of its appendages, leading also a 
pelagic or free-swimming existence. Each stage of growth is marked 
by the casting off of the outer skin or shell and the formation of a new 
one. The early transformations are quite rapidly accomplished. The 
history of the embryo at this time was carefully recorded by Prof. 
Ryder, who found that six molts occurred during the period of their 
free existence, which occupied from six to seven weeks in the aquaria. 
The molts take place at intervals of four to fifteen or more days, if the 
larvm are well fed. During the first, second, third, and fourth stages, 
occupying about three weeks, the embryos have the essential charac- 
teristics of a low group of shrimps, called schizopods, their appendages 
being chiefly adapted to swimming. Witli each molt the embryo be- 
comes slightly larger and new appendages are added. Prom a length 
of 8 millimeters at hatching, they attain a length of 13 millimeters in 
the fourth stage. With the fourth molt, which gives rise to the fifth 
stage, having a length of 14 millimeters, the embryo loses its schizopo- 
dal characters, being abruptly transformed into a type very closely 
resembling the adults. Formerly transparent, its color now is a bluish 
green, with more or less brown in some cases. During the fifth week, 
or toward the close of this stage, the young lobster becomes less partial 
to its earlier pelagic life, and remains on the bottom a great j)art of 
the time. In the sixth stage it has attained a length of 19 millimeters, 
and in the seventh a length of 22 millimeters, the latter being reached 
at an age of about seven weeks. During these three last stages the 
body and its appendages have been rapidly assuming the form and pro- 
* The Metamorphosis of the American lobster, Homarus americanus H. Milne-Ed- 
wards. By J otm A, Ryder, American N aturalist, xx, No 8, pp, 739-742, August, 1886, 
