PLEUROBRANCHUS. 199) 
Shell subopaque, pellucid, elongated, straight-sided, lightly 
rounded in front, the dorsal margin suddenly reflexed and winged 
behind ; right back margin obtusely angled ; whorls 2, spire mamil- 
late, prominent; suture impressed toward the aperture, margin in- 
cised ; submembranous growth-strie regular, growth-sulei remote, 
interstices iridescent with frequent splendid dots; radial strize very 
obsolete, radial impression sublateral ; length 5, width 3 mill. 
St. Thomas, West Indies on corals in 3-4 ft. (Riise) ; also Guade- 
loupe. 
Pleurobranchus voisin du Pleurobranche orangé Desu., Journ. de 
Conch., 1857, p. 142.—? Pleurobranchus sp., Rana, Manuel, pl. ii, 
f. 4.—Berthella quadridens Morcu, Journ. de Conch., 1863, p. 29. 
The number of leaflets on gill is more numerous than in Pl. 
aurantiacus Risso, and the two species are readily distinguished: by 
the lingual teeth. In P. quadridens there are three denticulations 
on the recurved cusp, the two lower being smaller and equal, while 
in P. aurantiacus there are ten little and nearly equal digitations at 
the point. 
Morch’s reference to Rang for an illustration, is only one of his 
jests. See also Haliotinella patinaria Guppy. 
P. AREOLATUS Morch. 
Body soft, nearly prismatic, suboval, gibbous from contraction ; 
mantle suboval, rectangularly emarginate in front, back areolate, 
the areas oblong-hexagons, central ones rather smooth, those at 
sides smaller with a median wart, anterior marginal areas small, ob- 
solete, but with very distinct papille. Foot oval, the margin thin, 
undulated, anterior sulcus of foot gaping, laterally much reduced, 
sole narrowed behind, with a longitudinal sulcus glandulose on each 
side nearly one-third the length of foot. Veil above the mouth 
transverse, narrow, with subacute, slit lateral angles, the bases of 
the sides reticulated with small confluent purple spots. Tentacles 
with circular sulci, approximate, cylindrical, rolled, slit down the 
side and perforate at apices. Eyes large and black, midway be- 
tween bases of tentacles and the mantle. Gill plume long, triangu- 
lar, the sides subparallel, with about 16 alternating secondary 
plumes on each side, becoming smaller toward the apex, each with 
a strong wart at the base. Length 21, width 16, alt. 15 mill. in the 
contracted condition. 
