58 



nomenclature of the Australian and Tasmanian Crayfishes, and to 

 give diagnoses of the genera and species with their limits of 

 distribution. The work was based on a large material obtained 

 from all parts of the continent and from Tasmania, Many of 

 the specimens had been collected by the author, but the majority 

 formed a very large collection brought together during the past 

 twenty years by Prof. Baldwin Spencer. 



Four genera were recognised, Astacopsis, Chcerops, Parachce- 

 rops, and Engceii,s : the first three genera included the Freshwater 

 Crayfishes proper, and the last-named genus contained the Land- 

 Crayfishes, which were not dealt with in this paper. 



The geogi-aphical distribution of these genera and its bearing 

 upon the geographical problems of Australia was discussed, and 

 the view was supported that the Bassian Subregion represented 

 the home of the Australian Crayfish, and that Astacopsis was 

 nearest the ancesti-al form. 



Mr. F. E. Bbddard, M.A., F.R.S., F.Z.S., Prosector to the 

 Society, presented a paper on " A new Genus of Tapeworms from 

 the Bustard {Uuj)odotis kori)." Four complete specimens and 

 some fragments of this Cestode had been obtained from a 

 S. African Bustard in the Society's Gardens, and the author 

 regarded it as a member of the group Tetracotylea, but could not 

 reconcile its characters with those of any other genus of that 

 group at present known. He briefly described its anatomical 

 characters and discussed its systematic position, and proposed a 

 new genus and species for its reception. 



The Secretary presented a memoir by Mr. A. E. Cameron, 

 M.A., B.Sc, entitled " The Structure of the Alimentary Canal of 

 the Stick-Insect, Bacillus rossii, Fabr., with a Note on the 

 Parthenogenesis of this Species." 



The author stated that this insect had a rather limited dis- 

 tribution, occurring in the south of Europe and in the north of 

 Africa, and that in the wild state it was not found north of 

 Orleans. Certain peculiarities of the alimentary canal were dealt 

 with which were regarded as adaptations to the mode of life of 

 the species. Attention was di-awn to the fact that the male was 

 only rarely found in the wild state, and that parthenogenetic 

 i-eproduction of B. rossii had been verified, for during four 

 generations the specimens kept by the author had showed no 

 males. The fact that the males were disappearing suggested that 

 parthenogenesis was not the primitive method of repi-odiiction, 

 but that the species had become adapted to it through the failure 

 of sexual reproduction, 



Mr. H, B. Preston, F.Z.S., communicated a paper based on a 

 collection of Terrestrial and Fluviatile Shells made by Mr. Robin 

 Kemp in British and German East Africa. One new genus and 

 thirty-four new species were described, which repi-esented only a 

 very small portion of the large number of species collected 



