NATICIDA. 209 
Distr.—10 sp. Norway, Great Britain, Mediterranean, New 
Zealand, Philippines. Fossil, 2 sp. Pliocene. 
Shell ear-shaped; thin, pellucid, fragile; spire very small; 
aperture large, patulous ; inner lip receding. No operculum. 
Animal much larger than the shell, which is entirely concealed 
by the reflected margins of the mantle; mantle non-retractile, 
notched in front; eyes at the outer bases of the tentacles. 
~ Lingual uncini 3, similar; or one very large. 
Lamellaria perspicua (1xiii, 57, 58) lays its egos in February 
and March; it hollows out a nest in the colonies of the com- 
pound Ascidians, from which it derives its nourishment. The 
nest is closed by a transparent operculum, presenting circular 
and concentric strive, showing that the animal turns round during 
oviposition. Each capsule contains besides the normal eges a 
certain number of rudimentary ones, which later serve for the 
nourishment of the embryos. The first shell formed is nautiloid, 
presenting two dorsal and two lateral keels (xx, 49, 50); the 
second shell, formed within the first, is more simple, like a Cari- 
naria: the two are united at their apertures by a thin membrane. 
—GIARD, Comptes Rendus, 736, 1875. 
Dr. J. Gwyn Jeffreys remarks of the same species :— 
The mantle, tentacles and foot assume different positions when 
the animal is quiescent and in active motion. It swims or floats 
with apparent ease. The gill-plume (whether single or double 
I could not make out) is of a yellowish brown color. Mr. Daniel 
found constantly in the stomach portions of branched corallines, 
probably indicating that the Lamellaria feeds on Polyzoa. 
According to Mr. Peach the female eats a round hole in a jelly- 
like compound Ascidian (Leptoclinum punctatum) for the purpose 
of making her nest and depositing in it her eggs. This nest is 
pot-shaped, and covered by a circular lid; it is at first bright 
yellow, which afterwards sometimes fades and changes, becoming 
at last dirty white. As the embryo increases in size the nest 
rises up beyond the surface of the Ascidian, having been pre- 
viously covered on all sides. The spawn is deposited from 
February to May; it arrives at maturity in four or five weeks. 
The embryo, when enclosed and swimming in the glairy matrix, 
is of a somewhat triangular shape; the front portion is trilobed, 
each lobe being furnished with delicate vibratile cilia which are 
in constant motion; the central portion is granular, and the 
hinder bluntly pointed. On the pot-lid bursting open and the 
fry emerging, the latter is found to have a pellucid nautiliform 
Shell, retaining in other respects the appearance of its foetal 
state, and destitute of tentacles, eyes or foot. Mr. Peach’s ex- 
cellent observations were continued regularly for ten years. 
Every season the Lamellaria,as if impelled by the same instinct 
