LIFE HISTORY OF THE BLUE CRAB. 127 
Fig. 9B. Spermatozoa from the sperm sacs of females, some of which had previously spawned one 
batch of eggs. 
Fig. 10. Hair from swimmeret of blue crab, bearing empty shells of the eggs from which the young 
have hatched. The presence of such fragments of a sponge upon the swimmerets of a female crab is 
proof that she has spawned at some time. Individuals may be found in considerable numbers with 
such remnants during the winter and spring months. 2s. 
Fig. 11. Reproductive organs of male crab. A, testis; B, gland secreting medium for transporting 
spermatophores; C, vas deferens; D, stomach; E, digestive gland. X14. 
Fig. 12. Egg taken from ovary and kept for 15 minutes in sea water; note swelling, manifested by 
distension of egg membrane; A, egg membrane. 
Fig. 13. Reproductive organs of adult female crab taken with the dredge on January 5, 1917, in 
Chesapeake Bay. A, ovaries, large, and filled with mature eggs. The sperm sacs are covered by the 
ovaries at this stage. 14. 
PLATE XLIX. 
Fig. 14. Ventral view of adult male crab showing copulatory organs. 
Fig. 15. Copulatory organs of male crab. Black paper has been placed behind the ducts leading 
from the reproductive organs. A, vas deferens, duct leading from the testis out through the inner joint 
(coxopodite) of the leg to the intromittent organs; B, intromittent organs. 
Fig. 16. Ventral view of adult female crab showing swimmerets. A, inner swimmerets to which 
the eggs are attached; B, external openings of oviducts. X 12. 
PLATE L. 
Fig. 17. Photograph of reproductive organs of female crab shortly after copulation, showing sperm 
sacs large and distended by the jelly carrying the spermatozoa from the male. O, ovary; S, sperm sacs; 
L, digestive gland. 
Fig. 18. Photograph of female crab upon whose swimmerets remnants of an old sponge were found, 
thus showing that the individual had spawned. This crab was taken with the dredge on February 28, 
1917, in Chesapeake Bay. Note large, full appearance of ovaries, O, which are filled with mature eggs; 
L, digestive gland. 
Fig. 19. Female crab bearing what is known to be at least the second sponge. Remmants of an old 
sponge were found upon the swimmerets when she was taken on April 24. This individual was kept 
under observation in a wire cage in the water of Hampton River. On May 30 this sponge was formed. 
Microscopic examination during the next few days showed that the eggs were fertile and beginning 
to develop. X %. 
PiaTE LI. 
Fig. 20. Floats secured within an inclosure of wire supported on posts to prevent disturbance 
by boats. ‘ 
Fig. 21. Zoéa, form possessed by the blue crab when first hatched. (After Brooks.) X 8o. 
Fig. 22. Four crabs which were taken with the dredge during the spring of 1917 and which spawned 
in June of that year. The three without claws were kept under observation in a cove at Lynnhaven 
Bay, Va. ‘The one with the claws was kept in a wire cage in the water of Hampton River, Va. The 
two at the left are known to have spawned the preceding season as remnants of an old sponge were found 
upon the swimmerets of each of them when caught. 
Fig. 23. Megalops, second form of the blue crab, attained after molting from the zoéal stage. (After 
Brooks.) XX 8o. 
Fig. 24. Regeneration of the claws. When this individual was caught the left claw was lacking. 
At the first molt while in captivity the claw was regenerated, upper row; in the two succeeding molts 
the left claw practically overtook its fellow in size, middle and lower rows. 
PLATE LII (After Hay). 
Fig. 25. “‘Buster”’ crab, first molting stage. - 
Figs. 26, 27, 28, and 29. Successive molting stages. 
Fig. 30. Photomicrograph of eggs attached to hairs of swimmerets. A few empty shells from which 
the young have been hatched are shown. In many of the eggs, the eyes of the developing zo€éas may 
beseen. X 120. 
