102 CAMCENA. 



to the body-wall by a band of muscles ; duct of the spermatheca 

 long (pi. 18, figs. 1 and 3). 



Distribution of the typical forms, southern China (provinces 

 Kwang-Tung and Kui-chu) to Burmah and southward. 



The most important features of this genus are found in the genital 

 system, which is of the type called by the writer epiphallopliorons. 

 The penis is continued upward in a flagellum-like extension (epiph- 

 allus), in which the vas deferens enters, and which "enters the penis 

 itself through a penis-papilla (pi. 18, fig. 2). Thus far, the structure 

 is exactly like Caracolus of the West Indies; but Camcena differs 

 from Caracolus in having the retractor muscle inserted upon the 

 epiphallus instead at the apex of the true penis. The penis-retractor 

 is attached to the floor of the lung-sack. The female system lacks 

 all accessory organs, and the duct of the spermatheca is longer than 

 in Pleurodonte. The vagina has strong muscular walls, and is bound 

 to the adjacent right body-wall by a band of muscles (shown in pi. 

 18, fig. 1) ; this structure occurs also in the West Indian Thelidomus 

 (see p. 96). The teeth are of the Caracolus type, being character- 

 ized by the total absence of side cusps on centrals and inner laterals. 

 The specimens dissected were received from Dr. v. Mollendorff, with- 

 out the shell. I take them to be C. xanthoderma. 



The shell is rather large, capacious, solid, and generally roughly 

 sculptured. The Japanese sinistral helices (H. qncesita, etc.) have 

 been associated with Camcena, but they belong to a totally different 

 phylum of Helix. The columellar lip is rounded in Camcena, not 

 expanded in a flat plate as in Phania or A cams. 



Perhaps no group of Helices has been less understood by systema- 

 tists than this. Albers included several very diverse types in his 

 original list of species. Martens restricted the group to large, 

 capacious sinistral helices of true Camcena and the very different 

 group Eahadra. Pfeiff'er united the whole Oriental and Australian 

 series of Eahadra, Camcena and Hadra under the one name 

 Camcena. The present writer, in 1890, defined the natural 

 groups of Oriental Helices, and indicated the conchological char- 

 acters upon which they rest, restricting Camcena to forms having a 

 large nuclear shell. This work was criticised by v. Moellendorff 

 (Nachrbl. D. M. G. 1891, p. 195), and several improvements in 

 classification were suggested. These were in large part adopted in 

 a later paper by the writer (Nachrbl. 1892, p. 71). 



