THERSITES. 127 



The first may have been eocene, at which time the Australian land 

 snail fauna received the ancestors of Thersites (-\-Hadra, etc.), and 

 of Panda, Pedinogyra, etc. At this time the Hadra group was not 

 differentiated from Chloritis. Subsequent isolation of Australia 

 resulted in the spread of the Hadra group and its segregation into 

 the modern subgenera ; and during this interval the genera Thersi- 

 tes and Chloritis were differentiated, the one in Australia, the other 

 in Papua. It is probable that much of the differentiation of 

 Planispira and Papuina, which are so intimately allied to 

 Thersites and Chloritis, occurred now, although the bases of these 

 branches may strike still deeper. At all events, they seem to have 

 peopled New Guinea during this interval. The second connection 

 of Queensland with Papua was comparatively recent, although 

 remote enough to allow specific differentiation (see Hedley in The 

 Nautilus, March, 1893, p. 124), and at this time, as Hedley believes, 

 the Chloritis species invaded Queensland from the north, with 

 Papuina, Atopos and the land operculates. At the same time 

 Queensland gave to New Guinea its few species of Thersites (Sphce- 

 rospira broadbenti, etc.), and perhaps some other forms. 



THERSITES vs. HADRA. The present group as a whole has hith- 

 erto been known as Hadra Alb. (See v. Martens, Die Heliceen ; 

 Semper, Reisen ; Hedley, Proc. Roy. Soc. Q. and P. L. S., N. S. 

 Wales; Pilsbry, Man. Conch.), but the name Thersites has priority 

 of five years over Hadra. It has also prior position in Die Heliceen, 

 where it is diagnosed and restricted. In view of these facts, and of 

 the further consideration that the nomenclature of Helices is now in 

 a transition stage, we cannot refuse to follow the course indicated 

 by established rules of nomenclature. There is another bar to the 

 use of Hadra in a generic sense ; it is preceded in the pages of Die 

 Heliceen by Rhagada, and this would give the latter name priority, 

 for there can be no doubt that both belong to one genus. 



It is now obvious that the use of the name Hadra by German 

 writers on shells of China and Japan is founded upon a misconcep- 

 tion of their relationships. Part of the " Hadra " species of these 

 authors belong to Camcena, part to Euhadra, a group closely allied 

 to Campylcea, etc. 



The subdivisions of Thersites are not very well defined naturally, 

 but the following may be admitted : 



Subgenus THERSITES, in which the shell has rather a conoidal 

 spire and is yellowish or brown, generally banded, the spermatheca 



