HELIX-ISOMERIA. 145 



H. atrata PFEIFFER, Proc. Zool. Soc. Loud. 1852, p. 153 (De- 

 cember, 1852 !) ; Mon.ographia iii, p. 258 ; Conchyl. Cab., p. 366, t. 

 139, f. 1, 2 (1853). HIDALGO, Viage al Pacifico, Mol, p. 12 

 (1870) ; and in Journ. de Conchyl. 1870, p. 31. MILLER, Malak. 

 Bliit. xxv, p. 167 (1878). COUSIN, Faune Mai. Repub. de 1'Equateur, 



p. 68, in Bull. Soc. Zool. France, xii, 1887. JOUSSEAUME, Moll. 

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nouv. de la Repnb. de 1'Equateur, p. 17, in Bull. Soc. Zool. France, 

 1887. (Not H. airata Reeve.) 



H. atrata Pfr. differs in several respects from the shell figured and 

 described by Reeve under the same name ; and the latter form has 

 been separated and re-named as a distinct species by Jousseaume. 

 Reeve's name " atrata '' really has priority of publication, bearing 

 date of May, 1852, while Pfeiffer's description was not read before 

 the Zoological Society until December of that year. It is not really 

 necessary to raise this point however. Pfeiffer's " atrata " was in 

 MSS. in the Cuming collection before the publication of Reeve's 

 species, for Reeve quotes " Pfr. Proc. Zool. Soc. 1850 " giving no 

 page, for there was none because it was not described until 1852. 

 Reeve in his innocent irresponsible way rarely troubled himself to 

 look up a reference or description, and in cases where he did, his 

 struggles and floundering in the slough of synonymy are pitiful to 

 see. 



Hidalgo has given a fuller diagnosis than that of Pfeiffer ; it is as 

 follows : 



Shell nearly covered umbilicate, depressed, solid, shining, delicately 

 striate, and under a lens very minutely granulate ; blackish- 

 chestnut, minutely more or less dotted with greenish ; spire little 

 elevated, apex obtuse ; whorls 5, nearly plane, the last cariuated, 

 deeply deflexed at the aperture ; base turgid, constricted ; aperture 

 very oblique, subrhomboidal ; peristome thick, white, reflexed, 

 terminations joined by a thick cord of callous, right margin with an 

 obtuse conical tooth above the base, columellar margin dilated, half 

 covering the umbilicus. Alt. 20, diam. maj. 45, rain. 38 mill. 



The stride are well marked beneath the sutures, and some of them 

 are greenish. The form of the umbilicus will separate, at a glance, 

 this species from H.faunm Phil., a species very similar in characters. 

 (Hidalgo.} 



H. MAURITII Jousseaume. PI. 44, fig. 7. 



Narrowly umbilicated, globose-depressed, rather solid, very 



minutely granulate, obscurely plicate-striate and malleate, blackish - 

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