174 Mr. W. T. Blantorcl on the Animal and • 



in the central portion of tlie lingual membrane of Georissn 

 sarrita] in that of O. frustWum I saw, with some difficulty, 

 long conical spikes, like needle-points, about four in each row, 

 somewhat irregularly placed at a distance from each other. 

 They appear to be no more regular in number than in position ; 

 occasionally there are more than four, at other times some are 

 obsolete. The rows of lateral teeth are extremely oblique, and 

 consist of about ten distinctly tricuspid teeth near the centre, 

 passing gradually, as they diverge from it, into simple hooks, 

 Avliich are very numerous. In G.sarritajQiQ.^i. Godwin-Austen 

 represents the lateral teeth as bicuspid. 



In Georissa pyxis I found the tentacles to be represented by 

 very blunt, almost hemispherical lobes, with the eyes at their 

 outer bases. Capt. Godwin-Austen's drawings of G. sarrita 

 represent no tentacular projections whatever, the eyes being- 

 sessile on a kind of frontal lobe, much as in AmphihoJa. The 

 difference is very trifling, as the rounded lobes observed by 

 myself might easily unite to form one slight frontal projection. 

 The extreme minuteness of the animals necessitating the em- 

 ployment of a microscope for their observation, makes it diffi- 

 cult to ascertain the exact form of the soft parts, especially as 

 the animals only emerge very little from the shell. 



With reference to these additional observations, some change 

 in the generic character becomes necessary. The following 

 may be suggested : — 



Genus Georissa. 



Testa minima, imperforata vel vix perforata, couica, succinea, spi- 



ralitcr sulcata vel striata, apertura fere semicirculari vcl semi- 



ovata, columella callosa. 

 Operculum ovatum, haud spiratum, excentrice striatum, testaceiun, 



transparens, processu elongate iutus haud procul a basi marginis 



interui munitura. 

 Animal parvum ; tentaculis hemisphsericis (v. connatis ?) ; oculis 



sessilibus ; pede brevi, rotundato, operculum in medio dorso juxta 



aperturam fercnte. 



It is evident that neither in the shell, operculum, animal, 

 nor lingual dentition is there sufficient resemblance to Ileli- 

 cina to confirm the position I at first suggested for the genus 

 as the type of a subfamily of the Helicinida3. But I think 

 that the true affinities of Georissa can now be clearly ascer- 

 tained. 



Subsequently to the })ul)licatIon of my paper in flu*. 'Annals' 

 for 1 804, Von Martens pointed out, in the ' Malakozoologischc 

 JUiitter' for the same year, that the type of the genus llydro- 

 cena of Parreyss, //. cattaroensis, Pfr., differs entirely from 



