NUDIBRANCHS OF THE VANCOUVER REGION 1 77 



Idalia vancouverensis sp. nov. 



Body. — The body is somewhat limaciform but stout and high, it drops 

 away quickly behind the branchial plumes, leaving a leaf-like prolonga- 

 tion of the foot to form a tail. The rounded body is sharply marked off 

 from the foot by a fiangelike expansion of the latter. The dorsum is 

 marked from the sides by a low pallial ridge which bears papillae and 

 passes round in front of the rhinophores. The papillae on the ridge 

 number 9 or 10; 4 around the base of the rhino phore the one in front 

 and median to it being smaller than the others, 3 or 4 between these and 

 the branchiae and two behind the branchiae. Inside these again and 

 slightly median to the rhinophores is a row of 5 papillae and finally 

 scattered irregularly in the mid dorsal region are 10-12 papillae, more 

 numerous just in front of the gills. All the papillae are about the same 

 size and shape being fairly long cylindrical and tapering to a blunt point. 

 A veil is present continuing out laterally to the head in the form of two 

 small triangular flap-like oral papillae. The genital aperture lies on the 

 right, well down on the side and behind the level of the rhinophores. 



Colour. — I have not had an opportunity of examining this species 

 alive so cannot describe its colour. In formalin it is of a dull greyish 

 white, faintly tinged with pink and showing no distinctive marking of 

 any sort. 



Dimensions. — ^The largest specimen measured preserved 18 mm. long 

 by 9.5 mm. wide and 8 mm. high. 



Head. — The head is broad and thick and bearing a longitudinal slit- 

 like motith. As noted above there is a small but distinct veil carried out 

 laterally as flap-like oral papillae. 



Foot. — ^The foot is quite large with an undulating margin that pro- 

 jects out beyond the body. Anteriorly it is slightly concave and pos- 

 teriorly continued into a flat tail terminating in a point. 



Rhinophores. — The rhinophores are cylindrical long and tapering to 

 a blunt point and not retractile. The stalk is quite short and the greater 

 part of its length is occupied by the perfoliate clavus which bears 28-30 

 deep leaves. It is apparently directed vertically and slightly upwards 

 and outwards. 



Branchiae. — The branchial plumes are simply pinnate and arranged 

 in a broad horseshoe with slightly uncurved ends. They are fourteen in 

 number and the anterior pairs noticeably larger than the posterior. In 

 the space between them is the anal aperture upon a well marked cone 

 on the right of which at the base is the renal pore. 



Radula. — ^The quite pale teeth are arranged in 22-25 rows, each row 

 consisting of 4 teeth. The two inner teeth are strong and hamate with 



