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MONOGRAPH OF THE ATLANTIDAE. 



succeeded in obtaining absolute certainty about them, 

 though believing they may be recognized in the future. 

 They are; 



A. invoUiia Souleyet (= A. turricidata F Souleyet), type lost. 



„ quoyana Souleyet {= A. inflata? Souleyet), type lost. 



„ quoyana Yayssiere A, helicinoides ? Souleyet). 



„ incliuata „ (his fig. 90) (= A. inflata F Souleyet). 



„ 'primitia Gould ) 



. , ) (=■ A. lesneun? Souleyet). 



„ cimiciila „ j ^ ^ 



So there remain only 12 names, which, in my opinion, 

 refer certainly to distinct species : 



A. pero?ii Lesueur. 



„ steindaclineri Oberwimmer. 



„ afli7iis Tesch. 



„ gaudichaudi Souleyet. 



„ lesiieiiri „ 



„ inflata „ 



„ helicinoides „ 



„ depressa „ 



„ fusca „ 



„ turriculata d'Orbigny. 



„ inclinata Souleyet. 



„ gihbosa „ 



These species may be arranged in different groups, as 

 I shall try to show. Not ascribing to these groups the 

 value of subgenera, I shall call them simply after one 

 species which may serve as the type of the group. It 

 appeared impossible to me to comprise in short diagnoses 

 the very slight difierences among the species, and so 1 

 thought it sufficient, for the sake of provisional orientation, 

 to give the following key. 



Key to the groups. 



1. Shell very flat, whorls all in nearly the same plain, 

 spire scarcely or even not at all projecting beyond the 

 last whorl, outer lip generally deeply fissured; keel (in 

 adult specimens) often penetrating between the whorls, so 

 that even the whole penultimate whorl may become encircled 



Notes from the Leyden Miuseum, Vol. XXX. 



