UMBRACULUM. nua 
the anterior slit. Mantle with thin edge fringed by numerous flat 
processes. Gill a long plume arising in front under the mantle, and 
continued along the right side, its latter end free and bipinnate. 
Radula extremely wide, composed of an enormous number of per- 
fectly similar, very narrow, needle-like teeth, strongly recurved to- 
ward their apices, the cusps narrowly lanceolate and smooth. 
Type Umbraculum sinicum Gmel. 
The radula of Umbraculum siniewn which I examined, has more 
numerous teeth than any other mollusk known to me. Among 
Tectibranchs, Dolabella has a somewhat similar type of teeth, but 
they are wider and much larger. The general characters of the 
teeth are as in Plewrobranchide. 
’ The name Umbraculum of Schumacher is the earliest tenable de- 
signation for this group, although it had previously been recognized 
as a genus distinct from Patel/a by Lamarck and Muhlfeld. There 
are several names anterior to the one commonly known, Umbrella 
Lam. 
DistriBution: The genus occurs in tropical and subtropical seas 
of both hemispheres, and is represented in the Eocene of Europe 
and America. The U. planulatum Conrad of Jackson, Mississippi, 
rivals in size the largest recent species. Two Jurassic forms, of 
doubtful pertinence to the genus, have been described. 
There are but few species, either fossil or recent, and the concho- 
logical characters separating them are neither very obvious nor of 
much value. The soft parts of U. mediterraneum and the Sandwich 
Island form of U. sinicum only are known. 
Species of Umbraculum. 
Panamic region: U. ovalis. 
Antillean region: U. plicatulum, bermudense. 
Mediterranean region: U. mediterranewm. 
Indo-Pacific and U. sinicum, E. Africa to Hawaiian Is. 
[Australian regions: U. cwmingi, Réunion Island. 
U. pictum, Lord Hood’s Island. 
U. corticalis, South Australia. 
U. ovauis Carpenter. PI. 70, fig. 61. 
Shell similar to U. indica, but the margin scarcely undulating ; 
regularly oval; apex spiral, somewhat projecting, less inequilateral ; 
12 
