LIFE HISTORY OF THE BLUE CRAB. 99 
Dr. Binford observed a crab which was kept in an aquarium while it passed from 
the megalops stage to that of the sixth crab stage.* The following table sets forth the 
results: 
TABLE A. 
Date molted. Stage. bi al THerease: 
(eee a| [SS 
Inch. Inch 
Jaly 18.5.5 6 ets soe eee ce AM eae ae naloeh onan seaisitoweusendaeesees Megdlopsi i... csc. ccccteceweesnce aT, ol smartest 
JULY 29. .06-- eee occa e eee ce eeec ne tene esos aaaesscnedeseereesedecnsses Rirepirabyeee..civecnies sides samiciss 128 0. 088 
Jully 27.0... 2.00 e nce e eee e en nnee nec enensinwenesscesseceaeenenccnsoeess Sore CSA sein seas seis easels 196 068 
ATIGUSt in sei oo occ on Shlania enw owing ules geen alee MMe dene ee gue n sane dij hint ae ls ya e ANE So Seo Goa ee 260 064 
August 6.....55 0-00 ec cece dense essen eee bane csen ced ddedecsocctsrerce Dini tid les |? SSG Ee Ip BOOOU a oer ic 348 088 
Avig“ist 12.....5-2 0c 0ccccecednccec cee ereberterssceeddendeceeedeceaees ANGER CTA D Gace ascii eotsw a bins oats 456 108 
PASIGUISE AS. ski soe eee smiewidtne ccs cen wale one anes baiele diese se sscnee SEMA eedtatine age aopronese +516 060 
This crab was caught in its natural habitat while in the megalops stage and 
placed in the aquarium on July 18. It changed to the first crab on the next day. 
The zoéa and megalops stages, therefore, were completed by about the middle of July. 
In the region of Beaufort, N. C., where this experiment was carried out, the bulk of 
the young hatch during June; therefore, probably not more than one month had 
elapsed between the hatching of this specimen and the time of confinement in the 
aquarium. That is to say, not more than a month was required in which to com- 
plete the zoéa and the megalops stages. 
The author succeeded in carrying several crabs through certain of the molting 
stages between the sixth crab and the adult. Some of the crabs were kept in floats, 
but most of them were confined in cages of quarter-inch mesh wire (Pl. LV, fig. 
38). These were placed on the bottom, in the water of Hampton River, at a depth 
of 4 or 5 feet at low tide. Each cage was equipped with a strand of wire by which it 
was lowered and raised and which was attached at its upper end to a stake. Although 
it was impossible to carry a particular crab through its entire life cycle, by begin- 
ning the experiment with crabs of different sizes, the author was able to collect data, 
from which it is possible to estimate how many moltings occur as the crab develops 
from the sixth crab stage to the adult size. It must be kept in mind that at this time 
of life the successive stages of the crab are very similar, except in size. This last also 
varies with the individual, the temperature, etc., so that it can not be ascertained 
by examination in just which stage a particular crab is. The best that can be done 
is to try to form as accurate an estimate as possible of the number of times a crab 
usually molts while reaching adult size and the time required to attain maturity. 
The results obtained by the author are presented in Table B. 
@ Binford, op. cit., p. 2. 
