178 Transactions of the Royal Canadian Institute 



the slightly curved spine almost at right angles to the base. The spine 

 bears a series of 5-7 small denticulations. The lateral teeth are smaller 

 and have a curved triangular base bearing a claw-like spine. 



The lips have an armature of tiny plates forming a ring. 



The penis bears minute hooks. 



The characters of this form are so distinctive that there is no doubt 

 as to its belonging to the genus Idalia which has not been previously 

 recorded from the Pacific coast of N. America. It is different in external 

 features and in the radula from any other species so far described and 

 so has been placed here as a new species under the name Idalia van- 

 couverensis. 



Habitat. — The three specimens examined were obtained from Rosespit 

 at the north end of Queen Charlotte Islands on 24, 7^06 and was probably 

 dredged in fairly shallow water of from 10-15 fathoms. 



Tribe B. Cladohepatica. 



The liver does not form a single mass but is divided, and in the 

 majority of families ramified. In a number of families the radula is not 

 ascoglossan, and jaws are invariably present. 



Family Pleurophyllididae. 



" A very distinct family which has apparently been specially modified 

 for a burrowing life. Animals of a fair size, fiat, oval or tongue-shaped, 

 and of leathery consistency. Head with a tentacular shield behind which 

 is a sort of neck bearing retractile rhinophores. No dorsal appendages. 

 The margin of the mantle usually bears cnidophores, and underneath it 

 are usually branchial lamellae. Radula broad, jaws strong, liver ramified. 



Genus PleurophylLidia (Meckel). 

 Pleurophyllidia Bergh, System der Nudibr. Gasterop., 1892, p. 68-72; 

 Bull. Mus. Comp. Zol., Harvard, Vol. XXV, No. 1894, p. 159. Eliot, 

 Brit. Nud. Moll., Pt. VIII, 1910, p. 160. 

 Cnidocysts and branchial lamellae are present. The anterior pallial 

 margin forms a continuous fold behind the rhinophores, and in front of 

 them there is usually a special prominence known as the caruncle. 



Pleurophyllidia californica (Cooper). 

 Pleurophyllidia californica Cooper, Proc. Califomian Acad. Nat. Sci., 

 Nov. 3, 1862, p. 202-207. Bergh, Weitere Beitr. z. Kenntn. d. 

 Pkurophyllidien. Verhg. d. k. k. zool. bot. Ges. im Wien, XL, 1890, 

 p. 3-8; Bull. Mus. Comp. Zool., Harvard. 



