338 Mr. Alder on the Genus Polycera. 
identical with the Doris flava of Montagu,) which have been 
described in a preceding Number of this Journal*. Of the three 
species which I have met with on our coast, one is probably 
the same with D. quadrilineata, Mull., and D. flava, Mont. ; 
the varieties I have met with inducing me to bring these two 
together. A detailed description may enable others to judge 
whether or not I am right in this view of the subject. 
Mouwusca Nupisrancui,, Cuvier. 
Fam. DORIDE, Johnston. 
Gen. Potycera, Cuv. 
a. With two branchial appendages, body without spicule. 
P. quadrilineata, Plate IX. fig. 1. to 6. 
Doris quadrilineata, Mull. Zool. Dan. t. 17+; Prod. 2771. 
Doris flava, Mont, Linn. Trans. vii. 79. t. 7. f.6. 
P. White, with 5 rows of orange tubercles, 4 to 6 tentacular fila- 
ments, 7 to 9 branchial plumes, and 2 branchial appendages. 
Variety, marbled with dark brown and orange, with 4 dark lines 
along the sides, uniting the orange tubercles. 
Body nearly half an inch long, limaciform, prismatic, tapering to 
a point behind, smooth, white, semi-transparent; with two mode- 
rately sized clavate and strongly lamellated tentacula, mucronated at 
top, tipped with orange, non-retractile; at a little distance behind 
which are two very small black eyes. The anterior portion of the 
body is produced into a kind of veil, the margin of which is adorned 
with four, or sometimes six, linear tentacular filaments tipped with 
bright orange. The sides of the mouth are produced into two angular 
points, but not tentacular. Seven, or rarely nine, plumose branchize 
are situated about two-thirds along the centre of the back. They 
are white tipped with orange ; the three anterior ones largest, the 
others very small, surrounding the vent in an incomplete circle. At 
the sides of these, and slightly posterior, are two plain, linear, 
branchial lobes, about three times the length of the longest plumes, 
abruptly tapering to an obtuse point, tipped with orange. Two 
rows of orange or golden yellow tubercles, extending from the mar- 
gin of the veil, form an elevated ridge on each side of the back to 
the branchial lobes, beyond which they unite and form a central 
carina to the fail. Another row of orange tubercles, not always 
regular, occupies the centre of the back, and two others adorn the 
sides between those first mentioned and the foot. Foot linear, very 
narrow, truncated in front, where it forms two sharp angles, and 
ending in a point behind. There is a strong groove down the centre, 
and the margins can be brought together like the leaves of a book. 
No cloak. The skin smooth and without any spicule. Aperture of 
the sexual organs on the right side, as in Kolidia. 
* Annals, vol. v. p. 92. 
+ For the quotation from Muller I am indebted to my friend Mr. E. 
Forbes. 
