DORCASIA. 173 



The dentition of D. globulm differs from that of alexandri in the 

 development of side cusps, which are represented in the hitter by 

 wide extensions of the mesocones. This is not an unusual variation. 

 The smooth low jaw recalls Helicophauta, but the egg is apparently 

 minute in Dorcasia, and we have from the mouth of the animal it- 

 self an emphatic contradiction of such a relationship, for the teeth 

 are totally unlike the unicuspid type of the Helicophanta and Am- 

 pelita group. 



The entire simplicity of the genital system shows Dorcasia to be- 

 long to the Euhaplogona, most living members of which are restricted 

 to America, Polygt/ra being a leading genus. In this group of 

 genera the penis bears neither epiphallus nor flagellum, the vagina 

 or atrium have no dart sack or mucus glands, the duct of the sper- 

 matheca does not branch into a diverticulum. Dorcasia is, there- 

 fore, isolated among the Helices of Africa, Asia and Europe. It is 

 interesting to note that many of its associates in the Cape fauna are 

 equally so, and mainly belong to a much older fauna than that 

 occupying these continents : Aerope has its allies only in Aus- 

 tralia, Tasmania and New Zealand ; Trachycystis (Pella) has the 

 same geographic alliances ; Peripatus has a similar, though wider, 

 range; and many other Cape animals could be named which belong 

 to an archaic fauna. 



With Oriental snails of the type of H. similaris Fer. (Eulotella), 

 these South Africans have no especial relations. 



All of the species are from the South African zoological province, 

 with the exception of the doubtful D. votiva Cr., from Madagascar, 

 which differs from all the other species in being banded. 

 D. rosacea Mull., iii, 213. D. lucana Mull., iii, 213. 



D. porphyrostoma M. & P., viii, D. inhluzana M. & P. 



[262. D. usambarica Crav., iii, 155. 

 D. globulus Miill., iii, 213. D. kraussi Pfr., iv, 50. 



Incana Lam., Fer., Rossm. D. cernua Mts., viii, 263, 

 D. namaquensis M. & P., viii, D. alexandri Gray, iii, 213. 



[262. v. minor Bttg., viii, 261. 

 D. gypsina Melv. & Pons., viii, v. rotundata Mss., viii, 261. 



[262. D. ? bulbus Mke., iii, 213. 



I), coagulum Mts., viii, 263. D. ? votiva Crosse, iii, 214. 



* * * 

 llelogona. 



The series of genera following are characterized by the possession 

 of organs wanting in all other Helices, viz. a muscular sack (or 

 sacks) on atrium or vagina containing a calcareous needle or dag- 



