PLEUROBRANCH AA. 225 
? Aplysia minor LANKASTER, Philos. Trans., 1875, p. 13 (embryo- 
logy). 
Pleurobranchea meckelii Leve, CANTRAINE, Malac. Méd. et 
Litt., p. 87, pl. 38, f. 3—VaysstERE, Rech. Moll. Opistobr., Tecti- 
branches, p. 130, pl. 5, f. 122-125. 
Pleurobranchidium delle chiaii VERANny, Catal. Anim. Invert. 
Mar. del Golfo di Genova e Nizza, pp. 16, 19 (1846). 
The mouth parts are always protruded in dead specimens. The 
species is very distinct from other Pleurobranchide of the Mediter- 
ranean. 
In establishing the genus Plewrobranchea, Leue gave no name to 
the species ; a fact which has been overlooked, probably on account 
of the rarity of the original paper. De Blainville was the first to 
use to use the specific name meckelii, which he ascribes to Meckel. 
It was never published by that author, however, Blainyille’s refer- 
ence in Man. de Malac. being a false one; and while it is possible 
that Meckel transmitted the specimens to Blainville under that 
name, no proof thereof is forthcoming, and propriety forbids the 
citation of Meckel as authority. 
Lankaster, with the embryologist’s disdain for exactness in small 
matters of species and genera, calls it Aplysia minor ! 
P. raRDA Verrill. PI. 53, fig. 86. 
Body subovate, stout, thick, often nearly half as broad as long 
usually less, tapering backward and blunt posteriorly ; front broad, 
convex or subtruneate; back more or less convex or swollen in the 
middle, with the surface wrinkled or irregularly reticulated, with 
the sunken lines brown, the reticulations smaller posteriorly. Dorsal 
tentacles short, stout, wide apart, ear-like, subtubular, having a slit 
on the outer side, with the edges often rolled in. Gill rather large, 
well exposed in a dorsal view, situated on the right side, behind the 
middle, and equal in length to nearly one-fourth the body, plumose 
bipinnate, with 15 or 16 pinnz on the upper side. Foot broad, often 
nearly as wide as the mantle, subtruncate or rounded in front, nar- 
rowed and obtuse posteriorly, ordinarily not extending beyond the 
mantle. The mantle edge is but little prominent, except along the 
right side. Proboscis protruded in most of the specimens, large, 
thick, obtusely tapered close to the end, which is emarginate, show- 
ing the large odontophore in a broad vertical notch. Reproductive 
organs large and prominent; the two orifices are situated on alarge 
tubercle in front of the gill. The male organ, in extension, is long, 
15 
