238 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 11$ 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 zoée obtained at the same time, and placed together ina . 
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 on a 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 appeared since the last 
observation, and under “dead” the number which had died since the 
last observation : 
| 
Time of observation. Zoéa. aaa Crabs. | Dead. 
UMEH ZO MCs MM alee heba ete ate aye ese he victoire a:oveis iis sic ets 15 | 22 0 0 
JUNC LAO ae Menace epee ee eens BANA Souci eetr | a | 23 2 7 
UCL ARO Var e. S Sele elae ere sia eiere Sete meta leet 7 Ge | De 2 0 
Dame Panwa iar tenet one eet eeee pepe Q | 22 1 a 
Shute hp. mit cula! Yates Heber eee LIS tees | 22 1 0 
JMIME Os. (Oras pM aes aree At clacisiecias te os eet Bae Oe 20 0 3 
MME. Ps MW avee ect ecklace decom eee Reece eeen, aces | 19 ie 0 
DUNC 26.6 AM amie emesis amex sects aainloes Se eal ace tee | 16 1 2 
JUNEe!27 16/8. Macs. oo 5 sence cea Se Soe ese ee | 14 2 0 
UMC 127 Oa DSUs ee aniey ian, ered ae ae ee sete eel eam ercle 12 0 2 
Sun pe erp amOee ae octetemiie elise eineei- elie hice ese cee Vere ow iil 0 1 
GMO SSH Melatowte steatosis lle mice ee cua sete siete BERRA eae | 9 2 0 
UNO PRAM MIM. ne Saree ae = Melee aa te a eee here ell eee ose | 4A 3 2 
BETES OOM ay MAME Sei Bey ee ees Coe A ee ee eae | “2 a Bes 
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 
