278 Dr. H. Lacaze-Duthiers on the Float of the lanthine. 
bus; canali recurvata; lacuna umbilicali magna; labro intus 
crebrilirato ; labio conspicuo, spiraliter rugose lirato. 
Hab. Sta Barbara, Pleistocene formation (Jewett). 
Col. Jewett’s single specimen is in very fine condition, and is 
confirmed by a fragment obtamed by Mr. Gabb, the paleeonto- 
logist to the California State Survey. Although resembling 
Purpura aperta and congeners in the irregular rugose folds of 
the labium, and Siphonalia in the strongly bent canal, Mr. H. 
Adams considers that its affinities are closest with the Cantharus 
group of Pisania. That genus is extremely abundant in the 
tropical fauna, but does not now live in California. It is the 
only distinctly tropical shell m the whole collection; and its 
presence, along with so many boreal species and types, appears 
somewhat anomalous, like the appearance of Voluta and Casst- 
daria in the Crag fauna. It is distinguished from the extreme 
forms of P. insignis by having the spiral lire pretty equally dis- 
tributed over the early whorls, by the close internal ribbing of 
the labrum, by the absence of the stout posterior parietal tooth, 
and by the great development of the columellar folds. 
Nofte.—Unfortunately, during the long interval which has elapsed 
between the transmission of the MS. and receipt of the proof, the 
types have been returned to the owner, and (with the remainder of 
Col. Jewett’s invaluable collection of fossils) have become the pro- 
perty of a college in New York State. As they are packed in boxes, 
and at present imaccessible, I am unable to give the measurements ; 
but the unique specimens were drawn on wood by Mr. Sowerby for 
the Smithsonian Institution.—P. P.C., Montreal, Feb. 22, 1866. 
XXX.—On the Float of the Ianthine. 
By Dr. H. Lacazz-Duruters*. 
Fasius CoLonna was the first to indicate the existence of the 
peculiar float of the Janthine, under the name of spuma cartila- 
ginea. Cuvier proved that this organ had no organic connexion 
with the body. “It is attached,” he says, ‘‘to the posterior 
part of the foot, almost immediately beneath the spot where the 
operculum of other genera occurs. I should be very willing to 
think that it is a vestige of the operculum which has undergone, 
in its form and tissue, changes similar to those with which na- 
ture presents us in so many of her other productions.” We 
shall recur to this last notion, which does not appear to be quite 
correct. Cuvier evidently had not observed the living animal, 
* Translated by W.S. Dallas, F.L.S., from the ‘Annales des Sciences 
Naturelles,’ série v. tome iv. pp. 828-341. 
