PLEUROBRANCHUS. 207 
passing the mantle behind, somewhat pointed. The mantle is a lit- 
tle raised behind to form a gutter below. Entire body reddish, 
covered with violaceous tubercles which are slightly yellowish; a 
brown band borders the upper surface of the foot. Labial tentacles 
long. Length not over 10 lines. 
Amboyna. 
P. cornutus Q. & G., Zool. Astrol., ii, p. 298, pl. 22, f. 20-24. 
Quoy & Gaimard remark that the individual described seems to 
be young. 
P. PERONII Cuvier. Pl. 48, figs. 24, 25, 26, 27, 28; pl. 74. figs. 
88, 89, 90. 
Living animal oval, convex, the mantle notched in front, shorter 
than the foot behind; closely covered with round, low tubercles, 
each on a red ground is bounded by a ring of deep crimson lake, 
with a dot in the middle (see fig. 28, enlarged). The sides of the 
foot are also dotted with this color. Veil slightly bilobed ; eyes 
distinct. Shell very delicate and thin. Length 2 to 3 inches. 
In alcohol the red color changes to a yellowish tint, and the re- 
lative proportions of foot and mantle are different, the foot becom- 
ing smaller; tuberculation of mantle obsolete. 
Port Louis, Mauritius. 
Pleurobranchus perontt Cuvier, Ann. du Mus. d’Hist. Nat., 
Vv, pp. 275, 266, pl. 18, f. 1-6 (1804).—Quoy & Gaimarp, Voy. de 
VAstrol. Zool., ii, p. 296, pl. 22, f. 7-10.—Desu. in Cuvier’s Régne 
Animal, Moll., p. 88, pl. 32, f. 1, a-i——-Marrens in Mobius’ Meeres- 
fauna Mauritius, p. 309.—SoweErBy in Conch. Icon., xvii, f. 2. 
Quoy & Gaimard declare the species described from life by them 
(see above) to be undoubtedly the same as that upon which Cuvier 
established the genus. The latter was much contracted in alcohol 
and had changed in color and form. An alcoholic specimen is 
shown in figs. 88, 89, 90 of plate 74, the figures being copies of 
Cuvier’s original illustration of P. peronit. 
The figures of Deshayes, cited above, are perhaps not referable to 
this species. 
Mobius thus describes the specimens found by him in Fouquets 
Bay, Mauritius: Dark purple-red, the back lighter in the middle, 
the mantle with low rounded warts throughout ; sole also dark pur- 
ple-red, but somewhat bluish. Shell likewise of a beautiful purple- 
