938 REpoRT OF COMMISSIONER OF FISH AND FISHERIES. [532] 
particular individual remained in this stage was observed only a few 
times. One full-grown zoéa (like the specimen figured) obtained June 
23, and placed in a vessel by itself, changed to a megalops between 9 
and 114 a.m. of June 24, and did not molt again till the forenoon of 
June 27, when it became a young crab of the form described farther on. 
Of two other zoéw obtained at the same time, and placed together in a 
dish, one changed to a megalops between 9 and 114 a. m. of June 24, 
the other during the following night; these both changed to crabs dur- 
ing the night of June 26 and 27. 
The following memorandum ona large number of the same lot of both 
stages of the young, kept together in a vessel of fresh sea-water, also 
indicates the rapidity of these changes. In the columns “ zoéa” and 
‘“‘megalops” the total number of individuals in each of these stages is 
given; under “crabs” the number which had appearéd since the last 
observation, and under “dead” the number which had died since the 
last observation : 
Time of observation. Zoéa. |Megalops.| Crabs. | Dead. 
June 23, 7 p. Uh... - 22 ween ene ee ee ee eee eee 15 | 22 0 0 
June 24, 5S anMarwieinsseee svn sees Sea Rte ae wd 5, 23 2 ih 
June:24,9 Ai Mises ces sews seed ermscteswaleey feee 4 22 2 0 
June 24, 115 a. mM... 2-20 ee ene eee ee eee ee eee 2 22 1 1 
JUD, T Pe Ni ass oc crassa sageitias sedeimecnmaese 1 22 1 0 
JUNO 25,6 Ais Wines a'sag.sercicics acter wean Ras esierlserateis 0 20 0 3 
Mune, 2 Ps Ms 12s cee ved seeeeeedeneesses fesse weiats | sie oe ersjeie 19 1 0 
JNA O: 26, 6: Gen Ts, cac0 -ainiiesers: orerdisceiereidicidueleisi ecb zenaia eiait note ote shee 16 1 2 
June 27,6 a.m.........- see Bi Speaetnne a tanec 14 2 0 
JUNE :27 5 QF Pi Whe onan seiee sieisiseie eeriswsisecde sewers Hoes esate 12 0 2 
Jane? po Mis.cdeascewccdece aca cu seepeeeevc |pese seer 11 0 1 
FUMES BN pe aaseteceo nce tecede see stres elie eee 9 2 0 
Juve 28, A PMs seis iticwinot s seenwascesswes terdone| eacscmee 4 3 2 
JUNE 29; 7 By Westies pase eves-tnes ceeeressedewnese wade cee 2 O° eave cies 
In the two or three instances in which the change from the megalops 
to the young crab was actually observed, the megalops sank to the bot- 
tom of the dish and remained quiet for some time before the molting 
took place. The muscular movements seemed to be much less violent 
than in the molting at the close of the zoéa stage, and the little crab 
worked himself out of the megalops skin quite slowly. Fora short time 
after their appearance the young crabs were soft and inactive, but the 
integument very soon stiffened, and in the course of two or three hours 
they acquired all the pugnacity of the adult. They swam about with 
ease and were constantly attacking each other and their companions in 
the earlier stages. Many of the deaths recorded in the above memo- 
randum were due to them, and on this account they were removed from 
the vessel at each observation. In this early stage the young crabs are 
