PROCEEDINGS I BIOLOGICAL SOCIETY 297 



E. P. Churchill, Jr.: The life history of the blue crab. Various 

 features of the life history of this form were studied by means of observa- 

 tions and experiments carried on during the interval from July 1, 1916, 

 to December 1, 1917, especial attention being given to the crab of 

 Chesapeake Bay. The eggs of the crab were found to measure about 

 1 100 of an inch in diameter. As they are laid they become attached 

 to the endopodites of the four anterior pairs of swimmerets, forming 

 the "sponge." About 1,750,000 eggs are laid- at one time. They 

 remain upon the swimmerets until they hatch, which event occurs 

 within about fifteen days after the,y are laid. Upon hatching the young 

 leave the female at once and do not cling to her as has often been 

 supposed. Most of the spawning in Chesapeake Bay is accomplished 

 from the first of June to the first of August and occurs mostly in the 

 southern part of the bay. 



About one month is required in which to pass the zoeal and the 

 megalops stages. After the latter stage is passed the crab molts about 

 fifteen times before the adult condition is reached. Most probably it 

 does not molt after reaching maturity. The young, which are hatched 

 in the southern part of the bay, migrate to Maryland waters and reach 

 maturity and mate there. There is a cessation of growth and molting 

 during the winter. Maturity is reached during the second summer, at 

 the age of about twelve to fourteen months. Mating occurs during 

 July and August. Mating takes place in the female at the time of her 

 last molting, at which time the abdomen changes from a triangular to 

 a broad rounded form. Most of the females do not lay the eggs the 

 same season in which mating occurs but migrate to the southern part 

 of the bay, he on the bottom in deep water there, and spawn the fol- 

 lowing season. The males do not migrate southward to as great an 

 extent as do the females, but remain in more northerly waters. The, 

 crabs do not bur}' in the substratum during the winter as has been 

 commonly supposed. 



At least two and probably three batches of eggs are laid by the 

 females. Some lay their first lot late in the summer and another lot 

 the next season. Some lay two batches during the same summer. At 

 the time of the only copulation which occurs during the life of the 

 female, enough spermatozoa are deposited b.y the male in the sperm sacs 

 of the female to fertilize all the eggs which she lays during her life time. 

 The females die shortly after the last batch of eggs is laid, death usually 

 occurring during the late summer or earty fall. The usual length of 

 life of the crab is about three years. 



The paper was illustrated by lantern sHdes. It was discussed by 

 W. P. Hay and Dr. T. S. Palmer. 



R. H. True: Notes on the early history of the pecan in America. 

 The earliest account of the pecan is probabty that by Cabeza de 

 Vaca, who saw it in 1533 on the lower course of the Guadaloupe River in 

 Texas. De Soto found it in use by the Indians in 1540-42 along the 

 Mississippi River from near the mouth of the Illinois River and south- 

 ward. The pecan seems to have been first introduced into the English 



