NATICID^. 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 ; ejes at the outer bases of the tentacles. 

 Lingual uncini 3, similar; or one very large. 



Lamellaria perspicua (Ixiii, 5*1, 58) lays its eggs 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 strise, showing that the animal turns round during 

 oviposition. Each capsule contains besides the normal eggs 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, Gomptes Rendus^ 136, 1815. 



Dr. J. Gwyn Jeffreys remarks of the same species : — 



The mantle, tentacles and foot assume diff'erent 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 j^ellowish brown color. Mr. Daniel 

 found constantly in the stomach portions of branched corallines, 

 probably indicating that the Lamellaria feeds on Pol^^zoa. 

 According to Mr. Peach the female eats a round hole in a jelly- 

 like compound Ascidian {LeptoclinuTn punctatvm) 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 bluntl}^ 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 b}^ the same instinct 



