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A SYNOPSIS OF THE GENUS ST7TREPTAXIS AND ITS ALLIES. 
By G. K. Guow mcr, 
Read 9th May, 1902. 
PLATE IV. 
Tue genus Streptaxis was established in 1837 by J. E. Gray,’ who 
included therein six species, i.e., S. comboides, S. Maugere, 8. contusa, 
S. deformis, S. nobilis, and S. pagoda. Of these S. pagoda has since 
been removed from the genus, being now regarded as pertaining to the 
genus Gibbus. Tryon, in 1885, enumerated 100 species, not including 
the species of Happia and Scolodonta, which then numbered fifteen. 
At the present moment the number of known species is 163, exclusive 
of Happia and Scolodonta, which contain thirteen and seventeen 
species respectively. 
Pfeiffer divided the genus into six sections: Artemon, Scolodonta, 
Ammonoceras, Hustreptaxis—the last being split into two groups, 
Odontartemon and Discartemon. Mons. Ancey proposed two further 
sections, Lamelliger for S. Zroberti, and Oophana for S. bulbulus and 
S. Michauwi; while Mr. J. W. Taylor contributed yet another section, 
Gonaxis, for his 8. Gibbonst. Tryon* rightly states that the 
peculiarities upon which the three last sections are based are 
shared more or less by several other species, and that the recognition 
of these sections could scarcely serve a useful purpose. He adopted 
Pfeiffer’s classification, except that he made Ammonoceras a subdivision 
of Artemon, united Scolodonta with it, and included Odontartemon as 
a third subdivision of Hustreptaxis. 
The next attempt to revise the genus was by Bourguignat,® who 
separated all the species with a non-deviated axis as not only alien to 
Streptaxis, but as having no affinity with the Testacellide. For these 
species he created a new family, Artemonidee, to be placed between 
Helicarionidze and Helicide, and to contain nine genera, viz. :— 
1, Gibbonsia, with one species, S. gigas; 2, Tayloria, for S. ventrosa 
and S. Jouberti; 3, Happia, new name for Ammonoceras, Pfr. (pre- 
occupied in Cephalopoda), type H. vitrina; 4, Scolodonta, Doering, 
type S. Sempert; 5, Drepanostomella, with one species, S. ammoniti- 
Jormis; 6, Colpanostoma, one species, S. Leroyt; 7, Artemon, Beck, 
type S. candidus; 8, Discartemon, Pfr., type S. discus; and 9, 
Alecidia, type S. Cypsele. Since these new genera are entirely based 
1 Mag. Nat. Hist., n.s., vol. i, p. 484. 
2 Man. Conch., ser. 11, vol. i, p. 57. 
3 Mollusques de |’ Afrique équatoriale, 1889, p. 36. 
