MATING BABITS OF Till BRACHYURA. 239 



The method of capture of the female by the male is tin- same 

 in these crabs as it is in the blue crabs. The ability of the blue 

 crabs to distinguish by siidit. however, seems to be greater. In 

 handling the members of the different species, one is -truck imme- 

 diately by the remarkable visual powers of the blur crab. He is 

 alert to moving objects and knows when a body comes \\ithin 

 striking <li-iance. 



Males of all three species were tested by removing the soft 

 female- and replacing them by hard males. They attempted in 

 all cases io copulate with the hard male-. Then iu the case of 

 the rO< k < rab, two male- wen 1 by placing \\ith them. hard. 



ovigerous female-, in which the -permatophore pin-- \\ere not 

 protruding. In tin -lit- male- -ucceedcd in in-ertin;.; the 



verges and actual copulation took pla- 



In th- M- male- \\ith whom vvciv placed other male-, the 



approach of ih< 'iil.'tin^ male to ihe -tr.m-er male 



\\a- made in a -imilar manner to hi- approach to the lo-i parliu r. 

 \\hen ill-- stl d violently, the <>ther male attempted 



to beat him into pa--ivitv iu-t a- he -iicce--fullv did \\ith the 

 female-, hard and fusl 1 ha\e | >rev iou-ly held in the 



:-h. I no\\ held that the ability of the male crab 

 to di-i iiu'ui-h tl llv a matter \ inabilitx to hold and 



copulate \\ilh the male iin li\ idual. It -eem- that discrimination 

 i- tactual and kin.e-ih 



Am-. n^ tin femali - captun-d for me \\ere fniir ovigerous lock 



i rabs, t\\ 'i ci'ab- and t\\o o\ i-erou- lad\ crab-, 



all of uliich had evidently been feriili/ed >ome time belmv, lor 



lhe\ were -m - --tully projected from a second teriili/alion. 



about ;, mm. around the aperture- of the -eminal recejiiacle-. 



the -hell Ua- -oft. Ill the o|>enin-- of the Vaginae \\ere -ecu I \\ o 



\i-h vermicular plugs. These were pulled out, the operation 



evidently cau-iii'., di-comfort to the female. The plii 1 ^- \\en- 



curved in such a manner thai tlu-\- appeared to have been moulded 



in the va-ina-. At the internal end- were the -permatoph' 

 eni|itied and Mat. In order I rinine if the-e -permatophofe 



plu^- were formed before they were vi-iblc from tin- out-ide, 

 I di ecieil a female \v hi ch had been killed tWO days after copula- 

 tion, and found that the plugs were present, but that the hanK 

 outer 1'in 1- \\ ere m 't \ n'< >\ rudin^. 



