108 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



This classification does not appear to be wholly satisfactory. 

 It is based chiefly on the relative development of the pallial 

 lobes, a comparatively trivial character, which Pilsbry himself 

 admits " is probably of secondary importance ", for nothing is 

 more likely than that these lobes may have undergone parallel 

 enlargement in different genera of the Zonitidte. Moreover, the 

 various characters which Pilsbry attributes to his genera and 

 subgenera are often not possessed by all the species which he places 

 in those groups. Thus, he describes his subgenus Angustivestis as 

 possessing an oval dart-gland and a shell without a spiral series of 

 punctures on the first whorl, and he also states (in his key) that it 

 has a foot excavated and laterally keeled under the shell. Yet he 

 includes in this subgenus H. schubotzi, which, according to Thiele,^ 

 has no dart-sac and a punctate protoconch, and H. kivuensis, 

 in which the anterior half of the top of the foot is stated to be 

 only somewhat flattened. Similarly, Pilsbry characterizes his 

 genus Mesafricarion as having a penial sheath, " to which the 

 penial retractor muscle is attached," and as lacking a dart-sac or 

 amatorial organ ; and yet his figures of the type species, H. 

 maculifer, clearly show that in it the penial retractor is attached 

 to the epiphallus above the penial sheath, as in H. cryptophallus, 

 while in H. jputzeysi the genital atrium bears a large excitatory 

 organ, which may well be homologous with the dart-sac of H. 

 hequcerti, H. semimemhranaceus, etc., notwithstanding that it has 

 has become enclosed in a common sheath with the anterior part 

 of the male duct. In the subgenus Granularion Pilsbry places 

 certain forms, some of which have never been described 

 anatomically, but which are said to agree in having the mantle- 

 lobes " wholly separated, or only quite weakly united by a narrow 

 rim in front ". An examination, however, of Germain's figure of 

 H. duporti,^ the type of Granularion, and of d'Ailly's excellent 

 drawings of H. pertenuis and the other species which Germain 

 included in his subgenus,^ shows that in these forms the pallial 

 lobes are united over the anterior edge of the shell, as in Pilsbry's 

 photographs of H. maculifer.^ Therefore, although it is, of course, 

 quite possible that H. duporti may differ greatly from H. maculifer 

 internally, until this has been shown to be the case it would seem 

 best to regard Mesafricarion as a synonym of Granularion, for 

 H. maculifer also agrees with H. duporti in having a granulose 

 mantle and a spirally sculptured protoconch. This, however, does 

 not necessarily imply that a new name must be found for the 



1 Deulsch. Zeniral-AjrlLa-Exped. (1907-08), vol. iii, 19] 2, p. 194. 



2 Bull. Mus. Paris, 1912, p. 257, fig. 58. 



^ Bihang K. Svensk. Vet.-Akad. Hand!., vol. xxii, pt. 4, 1896, pis. i, ii. 



* Bull. Amer. Mus. Nat. Hist., vol. xl, 1919, pi. xxii, figs. 1, la, 2. 

 H. issangoensis, another species included by Pilsbry in this subgenus, also 

 has fairly broadly connected pallial lobes, according to Thiele. 



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