198 Transactions of the Royal Canadian Institute 



spines getting smaller as they pass backwards but the first on each side 

 being almost as large as the median spine. They are relatively much 

 stouter than in C. rufibranchialis which this species resembles in certain 

 respects. The lateral tooth is in shape almost a right angled triangle 

 with a small piece taken out at the right angle comer. The apex is 

 continued as a sharp spine and the hypotenuse bears a series of from 8-10 

 small spines. 



Jaws. — The jaws are quite hollow and almost circular in outline. The 

 masticatory edge is fairly short and bears a series of tiny pointed denticles. 

 In general form the jaws are not unlike those of C. fusca. The genital 

 aperture is high up on the right side of the body about one third of the 

 way back. 



This species to a certain extent in its general appearance recalls 

 C. rufibrachiaUs of Alder and Hancock but differs in the presence of 

 opaque white lines, possessing a perfoliate clavus, wider flatter oral 

 tentacles and a different type of radula. In some respects it recalls C. 

 lineata but differs in shape of cerata, of oral tentacles and of the teeth. 

 It is here described as a new species, C. trilineata. It will be noticed 

 that both this and the preceding species have a perfoliate clavus with 

 quite shallow leaves. Examination under the binocular microscope of 

 the specimens .both alive and preserved shows that they are un- 

 doubtedly perfoliate although Eliot says that is not the case in the 

 genus. Sooner than form a new genus for this form and C. fusca how- 

 ever, I propose to place them with the other members and slightly 

 alter the diagnosis of the genus. 



Habitat. — The specimen was dredged in from 10-15 fathoms in 

 Nanoose Bay and was kept alive in the laboratory for some hours before 

 preservation. 



Family Aeolididae. 



j9 Uniseriatae. 



The radula consists of a single longitudinal row of teeth. 



Genus Aeolidida (Cuv). 



Alder and Hancock, Brit. Nud. Mill., 1854, Fam. 3, pi. 9. Bergh, Beitr. 

 z. Kenntn. d. Aeolidiaden I. Verh. d. k. k. zool. bot. Ges. in Wien., 



XXIII, 1874, p. 618-620— II, I, c, XXIV, 1874, p. 395-396— V, I, 



c, XXVIII, 1878, p. 822 ; system der nudibr. Gasteropoden (Semper 



Philippinen), 1892, p. 27; Bull. Mus. Comp. Zool., Harvard, XXV, 



1894, p. 127. Eliot, Brit. Nud. Mill., 1910, p. 175. 



Body stoutish, flattened. Comers of foot slightly produced, Rhino- 



phores smooth. Cerata flattened. Anus dextro-dorsal. Jaws with 



