INDIAN NUDIBRANCHIATE MOLLUSCA. 121 



which are rather imperfectly defined. The description of the under side is supplied 

 from Kelaart. 



Doris osseosa, Kelaart. (PI. XXVIII. figs. 10, 11.) 



Body elliptic-oblong. Cloak ample, firm, granular, greenish drab, with minute dark 

 spots : an elevated rounded ridge runs down the centre of the back, rising to a large 

 elevation a little in advance of the branchiae ; and an irregular network of small ridges, 

 uniting with the central one, covers the sides : the ridges are paler than the spaces 

 between them, and are covered with minute, obtuse, spiculose tubercles ; there are also 

 a few scattered tubercles in the spaces. Under side of the cloak pale, reticulated with 

 paler lines, giving it a sponge-like appearance. Dorsal tentacles rather small, clavate, 

 finely laminated, the laminae divided in front by a depressed line ; retractile within 

 distinct tuberculated sheaths. Oral tentacles small, pointed. Branchial plumes five (?), 

 tripinnate, spreading, retractile within a cup, the margin of which is scalloped and pro- 

 duced into a large lobe in front. Foot rather narrow, truncated in front, without 

 markings. Length from 2 to 2^ inches. 



Tongue like that of X). tuberculata ; no collar. 



Doris osseosa, Kel. in Journ. Asiatic Soc. (Ceylon Branch) 1858 ; idem in Ann. Nat. 

 Hist. 3rd ser. vol. iii. p. 298. 



Not uncommon. 



Doris tristis, n. sp. (PI. XXX. figs. 6, 7.) 



Body ovate-oblong, slightly raised. Cloak firm, coriaceous, with angular ridges and 

 swellings on each side of the back, and a few tubercular elevations at the sides ; the 

 surface is also covered with minute tubercles, particularly on the ridges and swellings, 

 and the hollow spaces between the latter are minutely reticulated with pale lines, the 

 interstices being dark or black: a deep depression occupies the centre of the back in 

 front, behind which is a large conical protuberance : the ground-colour of the cloak is 

 dusky olive, with a few scattered dark brown freckles on the sides and along the 

 margin ; under side of the same colour as the upper, minutely reticulated, and with a 

 few small black freckles. Dorsal tentacles retractile within elevated and minutely 

 tuberculated sheaths, of a dark olive-colour, with the margins pale and denticulated ; 

 the tentacles are rather small, with minute laminae divided in front by a depression ; 

 they are dark, with the tips white and pointed. Oral tentacles small, linear. Branchial 

 plumes four, tripinnate, spreading laterally, rather paler than the cloak ; the margin of 

 the orifice much elevated and undulated, and produced in front into a large erect lobe. 

 Foot ample, with a large deeply notched lamina in front, rounded behind, and extending 

 a little beyond the cloak in progression : the upper surface freckled with black. 

 Length 2 inches and upwards. 



R 2 



