Vol.XLVI June, 1924 No. 6 



BIOLOGICAL BULLETIN 



STUDIES ON III! -KCONDARY SEXUAL 

 HARA< TERS OF CRAYFISHES. 



i. MMI: SECONDARY SEXUAL CHARACTERS i\ 

 I'I.MMI- <n ('<;/ bams propinqitus. 



L. TURNER. 



ivvioRY. BELOIT COLLEGE. 



: In- ! the writer t"iun<l five -pecimciis 



'inn/Hint* f>r<>[>in<inn\ which had both m.ilc ,m<l Female second- 

 ary sexual characters. Two of tlie specinu n- were destro 



in di ectini; tin- iiiti-rii.il or-. ins, in examining tin- .innulus for 

 -pi iin ,m<l in -ep.iratini; the appendages preparatory to drawing 

 thrin. A r. \ir\\ i.|' the lit rr.it ure revealed that the r<m<Iiti(in is 

 <-xtrcinel\ rare. Many tin m-. i nds of specimen- ha\r < mr uml< r 

 thr do-r -i i ntin\ <.t Faxon, Eia^en, H.iy, Ortni.inn and others 

 .ind only thirti-c-n cases in the i:i-nus Canibarns h.i\'e Krrii rer. .nU-<l 

 in which ni.ile .nul I'em.ile -rc< >mlary >r\u.il character> ha\r Keen 

 fi.unil ti> r\i-t in the -.une indi\ idu.iU. The tiiulin.^ of the live 

 -pi cinieii- --ein- all the nmn- rein. irk. il >le U-can-e all were t.iken 

 within a -hurt distance of each other in Turtle ( 'reek near lieloit , 

 \\'i-con-in on a -iii;Jc field tri|>. Ahout two hundred -pecinieii- 

 were t.iken on the trip so that the >eeniin.u henna|)hroditic ones 

 con>titute<l about J.5 per cent, of the en tire catch. 



IHli^ent M-arch w,i- made in the same locality during the late 

 >prin^ with the result lh.it three more similar -pecimen- lieloii^in^ 



to the -.ime -pet ir- were found. 1 The ei^ht specimens are re- 

 ferred to in the descriptions as numbers i to 8 inclusive. 



The search was continued in l<J3 resulting in the capture of 

 four females in the >ame locality in Turtle deck. All showed 



imens described li.iv \-<-i\ :\ the Carnegie 



Museum at I'ittshurxli. 



1 8 263 



