96 BULLETIN OF THE BUREAU OF FISHERIES. 
The blue crab is especially abundant in Chesapeake Bay. This body of water is 
of sufficient size to afford a breeding ground for an immense number of crabs. ‘The 
young are very abundant in the region extending from the vicinity of Tangier Island, 
Va., to Baltimore, Md., the bottoms underlying the shallower waters of this part of the 
Bay forming, during the summer, a ground especially suited to the growth and molting 
of the maturing crabs. In the deeper waters of the southern part of the Bay the adult 
crabs lie on the bottom in vast numbers throughout the winter months. During the 
summer they frequent the more shallow waters, where they spawn in great abundance. 
DEVELOPMENT OF THE YOUNG. 
The young of the crab are hatched from eggs (Pl. XLVIII, figs. 1 and 7, and Pl. 
LIT, fig. 30), which measureabout 1/100 of an inch in diameter, * not as large as the period 
at the close of this sentence. When first laid, the eggs are yellow or orange in color, 
due to the color of the yolk granules within them, which serve as food for the young as 
development proceeds. As the eggs near hatching, this color disappears, and, since the 
eyes of the young are comparatively large and are of a very dark color, the mass of the 
eggs appears almost black. 
As the eggs are extruded from the body of the female they become attached to the 
fine hairs of the swimmerets on the under side of the abdomen. There are no swim- 
merets on the anterior segment of the abdomen, but there is a pair each on the second, 
third, fourth, and fifth segments, and none on the sixth or seventh. ‘There are thus 
eight swimmerets in all, four in a row on each side. Each swimmeret is made up of two 
branches, an inner and an outer (Pl. XLIX, fig. 16). The hairs borne by the inner are 
much finer and longer than those on the outer, measuring in diameter from 1/200 of an 
inch at the base to 1/700 at the middle.” The eggs all find lodgment on and are carried 
entirely by these hairs of the inner branches of the swimmerets, but never by the outer. 
Microscopic examination of these hairs, when they are bearing eggs, shows that each 
hair is covered throughout almost its entire length with a thin coating of a semitrans- 
parent material of a faintly yellow color. Each egg is attached to this covering by a 
separate short tendril of the same material, the hair and its burden resembling a long 
thin stem, with a great number of berries attached to it by short tendrils (Pl. XLVIII, 
fig. 7, and Pl. LII, fig. 30). From this resemblance, the crab, when bearing eggs, is 
sometimes said to be “in berry” or “‘berried.” 
There are eight tufts, or clumps, of eggs, corresponding to the eight inner branches 
of the swimmerets. These tufts are so large, however, that they are all crowded together, 
so that there is formed a flattish mass about 3 inches wide by 2 long by 134 deep, and 
fairly smooth in contour (Pl. L, fig. 19, and Pl. LI, fig. 22). From its general appear- 
ance and color, this mass is known commonly as a sponge, orange, lemon, punk, or 
ball. 
The egg color is yellow or orange when first laid, but, as already stated, it becomes 
almost black as hatching time approaches. The abdomen is pushed back by the sponge 
until it extends almost in a straight line with the body, except at the posterior end, 
where it curls downward behind the mass of eggs. 
a ‘The measurement given in this text was made by the author. The size is placed at 1/108 of an inch by F. H. Herrick 
in Natural History of the American Lobster. Bulletin, U. S. Bureau of Fisheries, Vol. X XTX, 1909, p. 310. Washington, rorr. 
b Herrick’s op. cit., p. 310. 
