Iredale. — Suter's "Manual of the New Zealand Mollusca." 451 



Estea gen. nov. 



The shell described by Webster as Rissoa zosterophila is selected as type 

 of this genus, which is as yet quite an austral evolution. When Melvill 

 and Standen met with a species from Lifu they were quite puzzled, and 

 referred it to Barleeia, a quite inadequate conclusion. Hedley (Zool. Res. 

 Fish. Exp. " Endeavour," pt. i, pp. 105-8, 1911) has referred them to Amphi- 

 thalamus, but that generic name should be restricted to the species grouped 

 around Rissoa scrobiculator Watson and R.jacksoni Brazier (= badia Watson). 

 These superficially agree with Amphithalamus inclusus Carpenter, but the 

 operculum of that species seems undescribed. Hedley has figured an 

 operculum in the mouth of his Scrobs pyramidatus (Mem. Austr. Mus., iv, 

 p. 354, fig. 77 in text, 1903), and this seems to agree with specimens I have 

 examined ; but I hope to deal fully with the genus Amphithalamus at a 

 later date. I have many species all clearly showing the " Scrobs " feature, 

 which never seems to me to merge into such a mouth as that shown by the 

 type of Estea. 



The difficulty of classing these is shown by the fact that the genus 

 Modulus Monterosato resembles a distorted Scrobs-like species, whilst the 

 genus Pisinna Monterosato suggests a combination of Scrobs and Estea, 

 agreeing exactly with neither. Yet when Sacco discovered a fossil like 

 Scrobs he named it Parmsetia ? mioscrobs&ides (I. Moll, del Piemonte, pt. xviii, 

 p. 32, 1895). 



Then Bartsch (Proc. U.S. Nat. Mus., vol. 41, pp. 289-91, 1911) de- 

 scribed west American species of Modulus, after having dealt with the 

 species of Amphithalamus (id., pp. 263-65), and thereto assigned shells 

 whose figures recall such as were assigned by Tate and May to Rissopsis 

 and Hedley to Epigrus. The species Tate and May put under Nodulus 

 Hedley has referred to Amphithalamus. 



When Hedley transferred Rissoa bicolor Petterd to Amphithalamus 

 (Zool. Res. Fish. Exp. "Endeavour," pt. i, p. 106, 1911) he noted, "This 

 seems synonymous with R. annulata Hutton (N.Z. Journ. Sci., ii, July, 

 1884, p. 173 : Proc. Mai. Soc, iii, 1898, p. 3) from New Zealand, over which 

 it has priority." I do not understand how this erroneous statement was 

 made, as Webster showed that at the second reference a very distinct 

 species was described, and that Hutton's R. annulata was only a form of 

 Hutton's R. olivacea, the type of Hutton's genus Dardania. The second 

 species he named R. zosterophila (Trans. N.Z. Inst., vol. xxxvii, 1904, p. 277, 

 pi. ix, fig. 5 (1905) ). and this is the type of my Estea. Rissoa bicolor Petterd 

 I refer to the same genus, but specimens (practically paratypes) of this 

 species in the British Museum agreeing with figures by Tate and May, as 

 quoted by Hedley and more recently figured by Gatliff and Gabriel (Proc. 

 Roy. Soc. Vict., vol. xxv, n.s., pi. viii, figs. 5, 6, 1913), are abundantly 

 distinct from Webster's species. 



I should consider that Hedley and May's Rissoa columnaria (Rec. Austr. 

 Mus., vol. vii, p. 117, pi. xxii, fig. 9, 1908) showed every character of Estea 

 clearly both in figure and description : " Aperture perpendicular, circular, 

 peristome reflected all round." 



Webster figured the operculum of R. zosterophila, and this disagrees 

 with that of Scrobs pyramidatus Hedley aforementioned. 



I suggest the inclusion under Estea of all the species Suter placed in 

 the subgenus Cingula, with which they have very little in common. 



I have more New Zealand species of Estea, and also species from Lord 

 Howe and Norfolk Islands, where Amphithalamus also occurs, but I only 

 procured examples of the latter genus from the Kermadec Islands. 



15* 



