; more
usually it assumes a dirty purplish lead-colour.

_Monstrous Variety._--Amongst a set of ordinary specimens from a ship
from Genoa, sent me by Mr. Stutchbury, there were three, one full-grown
and two very young, with the whole capitulum, (and likewise with the
scuta and terga taken separately,) not above half the usual length in
proportion to the breadth. Neither the colours nor animal in this
variety presented any difference.

_General Remarks._--This species is almost universally confounded with
_L. anatifera_. Quoy and Gaimard, however, appear to have distinguished
it, under the name of _A. tricolor_, from its colours. Leach named it
accidentally, for he specifies not one distinctive character, and
besides his two published names, he has appended two other names to
specimens in the British Museum. A specimen, from the Sandwich Islands,
sent by Mr. Conrad to Mr. Cuming, is marked _A. substriata_. In a dry
state, from the shrinking of the membranes, and consequent approach of
the carina to the other valves, and of the fork to the basal margin of
the scuta, it is most difficult to distinguish this species, though so
decidedly distinct, from _L. anatifera_; the absence, however, of a
tooth on the under side of the right-hand scutum is at once
characteristic. Even in specimens kept in spirits, in which there has
been no shrinking, but in which the colours have changed, and taking
into account the variation in the carina and upper part of the terga,
this species is not always readily distinguished from _L. anatifera_,
without opening the valves and looking for the right-hand tooth of the
latter. In fresh specimens, the orange ring at the top of the peduncle,
and the broad purplish interspace between the carina and other valves,
are characteristic. In all states, the filamentary appendages offer a
good character.

3. LEPAS ANSERIFERA. Pl. I, fig. 4.

L. ANSERIFERA. _Linnaeus._ Syst. Naturae, 1767.

ANATIFA STRIATA. _Brug._ Encyclop. Meth. (des vers), Pl. clxvi,
fig. 3.

PENTALASMIS DILATATA! (young). _Leach._ Tuckey's Congo Expedit.,
p. 413, 1818.

ANATIFA SESSILIS (?). _Quoy et Gaimard._ Voyage de l'Astrolabe,
Pl. xciii, fig. 11.

LEPAS NAUTA.[27] _Macgillivray._ Edin. New Phil. Journ., vol.
xxxviii, p. 300.

PENTALASMIS ANSERIFERUS. _Brown._ Illust. Conch., 1844, Pl. li,
fig. 1.

[27] Professor Macgillivray does not consider the species, which