M \I ENG HAB1 I- ' >F Mil BRA( HI OF \. 237 



The crabs were kept in a sea water aquarium 2 X - 1 .' X 4 

 feet. In the case of the blue crabs, observations and experiment- 

 were made only on those confined in this tank. The other species 

 \\ere -mailer and individuals were from time to time remo\ed 

 io circular bell jars, <> in. high and 9 in. in diameter, with about 

 o in. of sea water in them. 



Blue Crabs. The female about to moult is seixed by a male 

 and carried about by him for a day or two until she i- ready to 

 -lied lu-r -hell. I hiring the pre-nioulting period the female is in 

 a normal upright po-it ion, being held by the - < olid, third and 

 fourth pair of ambulatory appendage- of the male. It i- Mated 

 by I la\ l - that the male appear- able to distinguish the female 

 which i- about to moult. I \\a- not able to te-t thi- in the blue 

 crab-, but Iroiu tl, t\atioii- on the beha\ ior of the rock 



era' 1 < n irab- and lady crab-. I am inclined toquc-tioii the 



Matrmrni and to 1" 'hat the male i- not able to diM ingui-h 



the female about to nioul pt fr. .m the fart that -he i- less 



:ii. I ha\e noti-d this -luggi-Onie and apparent \\eakne-- 



in the i ra\ ii-ln everal days before moulting 7 . 



\\licn ti < :le i- in the pi Mioultiirj. -he i- left foi- a 



time b\ the mali I M n he approach- - her and turn- her over 

 so that her head i- beiic.ith hi- abdomen. I ua- unable tO 

 the lii-l ap|H"a< he- "I the male to tin -helled 



lemale. but -cparated t \\ < pair- man\ times and \\atchcd the 



readjustments. 



\\ hen the temale ha- been turned o that her \entral -urla< e i- 

 ap|)o-ed to that of the male, ami her hi ad i- -iuiated beneath hi- 

 abdoinen. both remain i|ir< - ral minuti-- nn!e-- di-iurbed. 



Alter a |.i iii"l ..I Irom thirt\ -ecoiid- to ten minute-, the male 

 tap- the temale li'JnK \\ith hi !ir-t and second ambulatory 

 appendage- and turn> her -lov, 1\ around underneath him. The 

 male is nut, how \er, the only active party. No -ooiier ha- the 

 female been an-u-ed f .mi her -emi-h\ pilot ic Mate \<\ the mo\ e- 

 ment and tactile Mimuli of tlu' male, then -he be^in- to u-e her 

 ambulatoiA a|ipendaui - in turning herself. In order to deter- 

 mine it an external Mimulu- would c.m-e an i arly adui-tmeiit, I 

 tapjied lightK on the edge of the thorai it iv J< m of (he l\-m.ile f 

 b\ mean- of the tip of a -mall seeker. This \\ a- tried oil tl. 



