THE ni ESTION OF REVERSAL OF ASYMMETRY IN 

 THE REGENERATING CHEIwE OF CRUSTACEA. 



CHARLES R. STOCKARD. 



I >urin- the summer of 1909 while at the Tortuga- Laboratory 

 I ill.- Carnegie Institution I undertook a further analysis of 

 the re\.T-al phenomenon in regenerating specimen- < >\ tin- p-iu-ra 

 Alf>hfn\ and .^ynul Aliens. These small Crustacea commonly 

 call. -1 -napping shrimp, on account of their habit of snapping 

 tin- lar^<- fin -l.i- \\ ith such force as to produce a -urpri-ingly loud 

 noi-.-, an abundantly found in the "logger-he. id" sponge and 

 in the holes of disintegrating coral rock on the Toruiga- reels. 

 There .ne a number of species five of \\hieh, Alpheus formosus 

 and tirniillatns and Synalpheus minus and two other unideiit itied 

 ^pecies of Synalphens, were employed in these experiment-. 



The several species differ in si/e and body color but are . 

 sentially similar in general structure. The lir-t pair ..I" appen- 

 es is decidedly asymmetrical in both sexes. < >m member <>t 

 the pair, either the right or the left, is extremely laixe. in some 

 cases being more than half the size of the bod\ it -ell". The 

 general t\'pe of this chela in the five specie- follou- IIK.K ..r 

 < l.p-ely the description given by Wilson, 1 for the vivai ehela 

 "I" AlplifHs lictcrochelis. It is greatly rounded or s\\olK-n \\iili 

 tran-\er-e grooves on either side of the proiiodu-. \ar\in.u in 

 de|)th with tin- -jwcies, and presents characteri-tie color patterns 

 beini; tip|)ed with a li\'cly rose color in Synalphcus minus while 

 in the other species it is bluish, dark or brown. On tin- e"iiea\e 

 sidt- of the dart\ln- is a swollen knob forming tin- "hami 

 which lit- intii a corresponding socket on the outer side of the 

 propodu- claw. M\- extending the dactylu- and then suddenly 

 -na|pini; the tlaus together the "hammer" is forced into tin- 

 socket with the surprisingly loud sound. 



XYil-i'ii'- de-cription further applies in that the large chela 

 ha- essentially the same structure in both sexes, while the small 



!". H., "Not.-- mi tin- Ki-vrr.-ul <>t A.-ynniK-try in the Regeneration -i 

 tlu- I'lu-l.i- in Alphciis hftcrochdis." BlOL. BrtL., IV'., pp. iv7 -'i-i. 1903. 



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