several new species of Nudibranchiate Mollusea. 313 
rendered still more probable from the fact that the skin isa tissue 
of cells, or perhaps is rather composed of a sort of network of 
vessels running in every direction and uniting in two large trunks 
that pass along the sides and pour themselves into the posterior 
angles of the auricle. The blood that comes from the skin con- 
sequently never passes into the true branchize. Cuvier, we are 
aware, states that these vessels empty themselves into the gills. 
With all deference to his high authority, we have convinced our- 
selves after repeated dissections that such is not the case, but 
that they go at once, as above stated, to the auricle. 
This fact is interesting, as it shows that even in those Nudi- 
branchs which have the branchi most perfectly specialized, only 
a portion of the blood passes through the gill; and when taken 
in connexion with the anatomy of Dendronotus, and with the 
peculiar form and internal organization of Humenis, goes far to 
establish the unity of the order Nudibranchiata. 
Doris diaphana. Body not much depressed, equally rounded 
at both ends, transparent yellowish white: cloak covered with 
rather large clavate tubercles. Tentacles nearly lmear, laminated 
with eight oblique plates ; apertures without sheaths. Branchial 
plumes eleven, simply pinnate, retractile within separate cavities, 
set in an imperfect open circle. Head with a large veil. Foot 
yellowish white, showing the liver through im a large dark patch. 
Length nearly an inch. 
Under stones near low-water mark on Meadfoot sands, Torbay. 
This Doris approaches nearest to D. bilamellata, but has much 
fewer plumes and is quite transparent and colourless. 
Doris pusilla. Body ovate, much depressed: cloak yellowish 
white, thickly freckled with dark brown spots, and having nume- 
rous conical papilla obtusely pointed at the top. Tentacles long 
and slender, pure white and finely lammated. Branchial plumes 
nine, beautifully white, simply pmnate, set m an incomplete, 
rather distant circle round the vent, and retractile within sepa- 
rate cavities. Head with a broad veil. Foot rather broad. Length 
about three lines. 
Under stones between tide-marks, Torbay. 
This pretty little species is not unlike D. depressa, but has the 
papillee less slender. The plumes are fewer and form a smaller 
circle, but are more conspicuous from their snowy whiteness con- 
trasted with the darker colour of the cloak. 
Doris subquadrata. Body rather elevated, white with a slight 
yellowish tinge, semitransparent. Cloak small, scarcely covering 
the head and foot, a little squared before and behind, with the 
edge slightly raised, not very convex, thinly covered with small 
papillary tubercles. Dorsal tentacles finely laminated, retractile 
within short smooth sheaths. Branchial plumes seven, non-re- 
