Mr. W. H. Benson on Ianthina, Bolten. 409 



M. Montrouzier has omitted to state on what special grounds 

 he proposed to separate /. capreolata as a species. Morch has 

 accepted it without question ; but in none of the recorded cha- 

 racters, whether in respect to general form/ subperforation, 

 colouring, depth of the marginal sinus, form of columella and 

 base, carination, structure of apical nucleus, or bifariate sculp- 

 ture, does any distinctive character from /. exigua appear to be 

 discoverable. The shell from the South-eastern Archipelago 

 may be reckoned as the largest known variety. That from the 

 vicinity of St. Paul varies much in figure, one specimen having 

 the breadth equal to the length ; others present the usual shape. 



I. nitens, Menke. 



This shell, of a uniform translucent purple colour, with a po- 

 lished surface, only entered my towing net of a small size, my 

 largest specimen being 7 mill, in length. I have, however, 

 recorded the capture by one of my companions of fine examples 

 with their floats, which were carinate above, and composed of 

 large globules. No ovisacs were found attached to them. This 

 variety is distinguished from the shell figured by Reeve by its 

 somewhat depressed spire. The nuclei, which were taken on 

 one occasion, are of a pale greyish violet, with a large rounded 

 aperture, the columella not being elongated as in the more ad- 

 vanced state of growth. 



/. Smithice, Reeve. 



Having taken only two minute specimens of the shell, supposed 

 from its form and colours to be the young of this species, I 

 have neglected to record any particulars respecting the float or 

 animal. 



/. planispirata, Adams and Reeve. 



My largest specimen of this shell is only 9J mill, in diameter; 

 but one of my fellow-passengers took a large one, unprovided 

 with ovisacs, but with a perfect float, which I noted as being 

 elongate and convex, the globules composing it being large, ob- 

 long, and transversely disposed. I have remarked that the floats 

 may always be referred to the species to which they belong, 

 when once observed in attachment to a shell, each kind having 

 its peculiar form and mode of construction ; therefore in sepa- 

 rating species it is of great moment to attend to the float ; and 

 it is desirable that this part should be preserved in a dried state. 



It is quite sufficient to glance at the representation (pi. 11. 

 fig. 10) in the Voyage of the ' Samarang/ to see that the fig. 9 

 of plate 2 in the ' Iconica ' has no manner of resemblance to it, 

 having a wide depressed-conoid spire with rapidly increasing 

 whorls, instead of the depressed plano-convex spire with slowly 



Ann. $ Mag. N. Hist. Ser.3. Vol. vi. 27 



