INDIAN NUDIBRANCHIATE MOLLUSCA. 145 
Family HERMALIDA, Alder & Hancock. 
Genus PuyLLOBRANCHUS, nov. gen. 
Body elongate, flattened on the back, and angulated at the sides, without distinct 
cloak. Tentacles two, dorsal, longitudinally folded, bifurcate above, non-retractile. 
Head produced at the sides into angulated and folded expansions. Branchiz leaf-like, 
with distinct footstalks, arranged in several rows along the sides of the back and round 
the head in front. Anus lateral. 
The tongue of this genus resembles that of Hermea. In our species there are thirty- 
seven or thirty-eight short stout spines, in single longitudinal series, with seventeen or 
eighteen truncated denticles on each side. ‘The spines diminish rapidly in size in front, 
where the tongue is convoluted. 
PHYLLOBRANCHUS ORIENTALIS, Kelaart, sp. (Pl. XXXIII. figs. 18, 19.) 
Body elongated, but capable of great contraction, flattened on the back, and angu- 
lated at the sides, of an olive-green colour. Dorsal tentacles placed much forward, 
long, cylindrical, longitudinally folded through their entire length, and bifid above for 
about one-third down: the slit is posterior; the external surface has a few minute 
tubercles. Branchiz large, ovate, leaf-like, with long footstalks, arranged in crowded 
ill-defined rows along the sides of the back and round the head, extending backwards 
nearly to the tail: the peduncles are cylindrical, the foliaceous portion flattened into 
ovate laminz, with a minutely denticulated margin ; the upper surface is slightly con- 
cave, and a little hollowed below, where the margin of the leaflet is raised at the top of 
the peduncle ; its surface has four stout branched lines, radiating from the footstalk : 
more minute radiating lines are seen on the under side: the hepatic gland forms a beau- 
tiful dendritic expansion of a dark green colour, the stalk passing down the peduncle. 
Head flat above, inclined downwards, and rounded in front ; produced at the sides into 
foliaceous expansions, which are angulated behind, and extended into folded tentacular 
points. Foot dark olive, broad and ample, slightly arched and produced into blunt 
points in front, where it is laminated but not notched; behind, it tapers to a blunt 
point. There is a white spot on the back, with a slight swelling indicating the region 
of the heart. Length 24 inches. 
Proctonotus orientalis, Kel. in Journ. Asiatic Soc. (Ceylon Branch) 1858 ; idem, in 
Ann. Nat. Hist. 3rd ser. vol. iil. p. 492. 
This curious animal is not uncommon. There are six or seven specimens in the 
collection, but they are all too hard and brittle for anatomical examination. Mr. Elliot 
informs us that the branchial papillz are very liable to fall off, and that their loss does 
not seem to inconvenience the animal. It is occasionally found of a very pale green, 
without any tinge of olive. The native name for it is Aku-purugu (leaf-animal). 
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