158 Transactions of the Royal Canadian Institute 



Habitat. — It is the commonest Nudibranch in and around Departure 

 Bay being found in the tide pools and on the rocks during April, May, 

 June and July. Specimens have been obtained from Jesse Island, 

 Brandon Island, Newcastle Island, False Narrows, Mudge Island, etc., 

 and it has been dredged also at a number of points. Generally it is to be 

 found in association with the preceding species which it resembles 

 superficially in appearance and is also similar in habits, clinging to the 

 rocks as the tide recedes and remaining exposed to the air for quite long 

 periods in the comers and under ledges where it is not exposed to the 

 direct rays of the sun. The two species may be readily distinguished 

 on a little closer inspection by the following characters all of which 

 however may not be marked in one individual. 



Anisodoris nobilis Archidoris montereyensis. 



Arched dorsum. Flattish dorsum. 



Generally bright yellow. Dingier brownish yellow. 



Branchial plumes lighter in colour Branchial plumes generally darker 



than the body. in colour than body. 



Plumes large and plumose. 6 in Plumes smaller and not so plu- 



number. mose. 7 in number. 



Plumes in circle joined at base. Plumes in almost a horse shoe free 



Oral tentacles auriculate flattened at base. 



and grooved. Oral tentacles digitiform. 



May reach a length of 20 cm. Maximum size about 50 mm. 



Large prostate gland. No prostate gland. 



Genus Diaulula (Bergh). 



Diaulula Bergh, Gattungen nordischer Doriden, Arch. f. Naturgesch, 

 XXXV, 1879, p. 343. On the Nudibranchiate Gasteropod Mollusca 

 of the North Pacific Ocean (Sci. Results of the Explor. of Alaska, I, 

 Art. VI), Proc. Acad. Nat. Sci. Philadelphia, 1880, pp. 40-46. 

 System der Nudibr. Gastero, 1892, p. 105. Die Opisthobranchien, 

 Bulletin Mus. Comp. Zool. Harvard, XXV, 10, 1894, pp. I7i-i75- 



Body fairly soft and depressed; notaeum silky minutely villous; 

 tentacles digitiform; branchial aperture rounded, crenulate, branchiae 

 tripinnate; foot rounded in front, bilabiate, upper lip notched in median 

 line. Labial armature none. Rhachis of tongue naked. Pleurae multi- 

 dentate, teeth hooked. Penis unarmed, prostrate large. 



