350 



to the third pair of legs in male specimens of Camharus fallax Hagen, 

 but my material was not in such a state of preservation that I dare to 

 affirm or to deny anything. Faxon mentions in his »Revision of 

 the Astacida«^ (p. 12 — 14) that among all the crayfishes he has exami- 

 ned, he has «noted four specimens, all of them Cambari^ that combine 

 external structures of the two sexes k*^. These were C. propinqims 

 var. Sanhornii Faxon, 1 C Diogenes Girard and 1 C. propinquus Gi- 

 rard. But he says that their state of preservation did not admit any 

 closer examination of the structure of the internal generative organs. 

 The question concerning the Camhari is therefore still apen. In the 

 common European crayfish Astacus astacus Lin. it has often been ob- 

 served that females are provided with masculine looking appendages on 

 the first abdominal somite. Dr. Bergendal has made investigations on 

 this subject and published his observations in a paper: »Über abnorme 

 Formen der ersten abdominalen Anhänge bei einigen Krebsweibchen « ^ 

 but in all cases recorded by him the abnormal crayfishes were females 

 and true females without any trace of hermaphroditism in the internal 

 organs and I have myself come to a similar result. The only known 

 case of complete hermaphroditism among the Decapoda seems thus 

 to be the lobster described by Nicholls 1730 which was provided 

 with masculine organs on one side and feminine ones on the other. 

 This was of course certainly a teratological case of singular kind not 

 dependent on any heredity. 



New and more extensive investigations on well preserved and 

 fresh material especially oi Parastacina are however needed before the 

 last word can be said concerning the rudimentary hermaphroditism of 

 these animals. 



The crayfishes treated above belong, as is already mentioned to the 

 species Parastacus Hassleri Faxon and are collected by Mr. P. Dusén 

 (I./ 10. 1896) at Taleahuano which is the same place from which 

 Faxon's specimens originated. They are thus topotypes to them. 

 They agree also in every respect with the description given by Faxon 

 except when he says : »The median carina of the inner branch of the 

 posterior pair of abdominal appendages ends near the hind margin 

 without developing a spine, (c I babe namely seen a small spine there 

 in some of my specimens, but this character seems to be variable and 

 is not even a sexual characteristic. 



The sides of the carapace covering the branchial chamber are 



5 Mem. Mus. Comp. Zool. Vol. X. Cambridge, Mass. 1885. 



6 On the same page is also a quotation from Desmarest and Rousseau 

 about a female Astacus astacus with branched oviducts.. 



7 Bih. K. Sv. Vet. Akad. Handl. Bd. 14. Stockholm 1SS8. ibid. Bd. 15. 1S98. 



