214 OSCANIUS. 
3, 3a (shell).—Monterosato, Nuova Rivista Conch. Méd., p. 48.— 
Susania testudinaria Cantr., MonrERosato, Nom. Gen. e Spec. 
Conch. Méd., p. 149.— Oscanius tuberculatus Delle Chiaje, Vays- 
SIERE, Rech. Moll. Opistobr., Tectibranches, p. 125, pl. 5, figs. 113— 
121 (anatomy). 
This is the largest species of the genus, attaining a length of 16 to 
19 centimeters. The shell is more oblong and more swollen than in 
other species of Pleurobranchus, and is, in proportion to the size of 
the animal, much smaller. 
The specific nomenclature is unusually involved, but the name 
proposed by Cantraine seems to be the earliest having a clear title 
to acceptation. 
O. TUBERCULATUS Meckel. PI. 51, figs. 50 to 57. 
Body oblong, the general tint ochrey red. Mantle not very 
thick, with irregularly scattered, unequal tubercles, which are never 
nearly so large as in O. testudinarius ; mantle rounded, emarginate 
in front, dark red with light spots, not as large as the foot. Foot 
voluminous, projecting all around the mantle, with a deep sinus in 
front, and a gland on the posterior median part of the sole. Gill 
covered by the mantle, folded longitudinally, quite long, with 23-34 
alternating pinnules on each side of the tuberculate rachis. Anus 
behind the insertion of gill. Genital orifices and renal pore in 
front of it; penis provided with two large triangular membranes. 
Length 12, width 11 centimeters. 
Jaws with the appearance of being carved, composed of small 
chitinous pieces, each terminating in a denticle, on each side of 
which there is one, sometimes two, smaller denticles. Radula with 
the formula 80.0.80, the inner 25 teeth having an external denticle 
below the terminal hook, which disappears on the outer teeth. 
Shell very large, occupying the greater part of the length of the 
mantle, quite convex, membranous, with growth lines, and of an 
iridescent vinous-red color; length of large shells 43, width 29 mill., 
or, in ordinary specimens, 25 to 30 by 138 to 15 mill. 
Mediterranean Sea: Gulf of Marseilles, in 30 to 70 meters ( Vays- 
siére) ; Algiers (Joly & Monts.) ; Naples (Tiberi); Adriatic Sea at 
Trieste (Stossich) ; Atlantic Coast of France; Southern England and 
Jreland. WUaminarian and Coralline zones. 
Pleurobranchus tuberculatus MEcKuL, Beytrige zur vergleichen- 
den Anatomie, i, pp. 33, 26, pl. 38, f. 33-37, 40 (1808).— PuILipPl, 
