NUDIBRANCHS OF THE VANCOUVER REGION 1 87 



flanked by lateral teeth. The median tooth has an oblong base and a 

 median spine Avhich is almost equilateral but slightly asymmetrical. 

 The sides of the spine bear only a short row of minute denticles not 

 nearly so extensive or well marked as those present in D. arhorescens and 

 the whole tooth is of a slightly different shape. The lateral teeth are 

 somewhat similar to those of the preceding species but relatively larger 

 and slightly curved and claw-like at the end. The outer surface bears a 

 series of about seven small spine like denticles but they are subject to 

 considerable variation in size, shape and numbers and may fail alto- 

 gether. The radula is composed of from 38-40 rows and the lateral teeth 

 number from 10-14 on each side. 



Jaws. — ^As in the preceding species the jaws are well developed and 

 they are of very similar shape. In the specimens examined the plate 

 was relatively slightly narrower and the superior process more developed. 



The penis is moderately long, sub-conical and unarmed. 



This species was named by Bergh (2) from a large bulbus pharyngeus 

 that was obtained by Dr. Wm. Stimpson. The same author subse- 

 quently described the species more fully from two preserved individuals. 

 Although he describes them fairly fully he says also in the same paper 

 " Der D. dalli is ebenso vielleicht nur eine blosse Varietat (of D. arhores- 

 cens) bei der jede Spur von Denticulation des erwahnten Schneiderandes 

 fehlt ". This is apparently accepted by Eliot who does not give D. dalli 

 as a species in his list. The question of what constitutes a species is 

 often a difficult one but in the present instance I think that there is no 

 doubt that D. dalli is to be regarded as a distinct and valid species. 

 Apart from the slight differences in the radula (fewer rows, more lateral 

 teeth, different denticulation on the spine of the median tooth, etc.) it is 

 always possible to distinguish the species externally; indeed they can be 

 separated from D. arhorescens without hesitation by a person imfamiliar 

 with them and this I submit is sufficient to justify regarding them as 

 separate even if closely allied species. 



Hahitat. — ^They have been dredged from various points in from 10-40 

 fathoms including Halibut Bank, Nanoose Bay, between Jesse and 

 Newcastle Islands, and Gabriola Pass. 



Dendronotus giganteus sp. nov. 



Body. — The body is fairly stout, long and high; it is considerably 

 higher than broad and not sharply marked ofT from the foot although 

 more so than in D. arhorescens, owing to the fact that the foot has a 

 wrinkled margin around which runs an opaque line of dead white. The 



