Mr. W. H. Benson on Ianthina, Bolten. 409 
M. Montrouzier has omitted to state on what special grounds 
he proposed to separate J. 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, cariation, structure of apical nucleus, or bifariate sculp- 
ture, does any distinctive character from J. 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. 
I. Smithia, 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. 
a 
I. planispirata, Adams and Reeve. 
My largest specimen of this shell is only 94 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 (pl. 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. 
