LIFE HISTORY OF THE BLUE CRAB. 409^ 



similar to that of the adult. A reference to the figure, however, will 

 show that the megalops is still far from being" like the adult crab. 

 There is still a long-pointed rostrum on the front of the shell, and the 

 e3"es, instead of being- hidden in cavities on the front of the shell, pro- 

 ject conspicuously from the sides at the base of the rostrum. Both 

 pairs of antenna? project from beneath the rostrum, and the lash of the 

 second antenna is very long. The last pair of legs are bent upward 

 and backward above the back of the shell and are borne on a separate, 

 movable segment of the body. The abdomen is still long and carries 

 five or six pairs of swimmerets; while the animal is swimming the 

 abdomen is stretched out behind the carapace, but while crawling it 

 may be bent forward under the ventral surface of the bod}", as in the 

 adult. The third pair of maxillipeds are still leg-like, being composed 

 of cylindrical segments, and are not flattened as ir the adult. In fact 

 the general structure and appearance are quite as much like that of a 

 cravfish or lobster, as like that of the familiar blue crab. 



The time required for the megalops larva to change into a young' 

 crab having the form of the adult has not been recorded, but is prob- 

 ably quite short. B3' successive molts « the outline of the shell, the 

 structure of the appendages, and the internal anatomy approximate 

 more and more closely the future condition, until at last, by the time 

 the animal has reached a breadth of perhaps one-fourth of an inch, its 

 trvie nature becomes plainly evident. 



Even before this time it has fallen in with others of its kind and 

 together with them it moves shoreward.* In Chesapeake Ba}^ this 

 general shoreward movement appears to take place early in the spring, 

 for at Crisfield in April, and to some extent in May, the tinj^ crabs 

 begin to appear in great numbers. The}^ float along with the currents, 

 clinging to bunches of grass or swimming freeh' in the water, and 

 finally find a suitable home in some shallow and sheltered bay or 



«The number of molts during the megalops stage is stated by Paulmier to be 

 (probably) six. 



&In Miss Rathbun's paper (p. 368) there is given an account by Mr. John D. 

 Mitchell, of Victoria, Tex., of the breeding habits of the crab in the Gulf of Mexico. 

 He says: "The eggs begin growing in the spring and hatch the latter part of May or 

 June, the young clinging to the apron for several days. When first hatched they 

 are very little more than two eyes, and look like anything but a crab. I know little 

 about the number of times the young sheds from the time of leaving the mother's 

 apron until it gets its crab shape, which is inside of three months. I have seen the 

 little fellows so thick near the margin that the water would look murky and thick,, 

 and thousands could be scooped up in the two hands placed together, and their cast- 

 off shells would form a gray streak along the water's edge. They collect in immense 

 numbers along j^rotected shores and nooks, shedding several times and getting their 

 shape in September, when they start on their great migration across the bays for 

 the north shores, where they enter the creeks and estuaries, and go upon the shoals, 

 where they remain until grown, burying themselves in the mud and sand in winter." 



