1 88 Transactions of the Royal Canadian Institute 



back is well rounded and smooth, high in front and dropping fairly 

 rapidly in the region of the fourth pair of papillae. A veil is present 

 which has three dendriform appendages on each side of which the outer- 

 most may be divided into two almost from the base. Under the veil 

 and upon the upper lip are a large number of papillae roughly arranged 

 in rows. The uppermost usually six in number are slightly branched, 

 the next row, five or six in number, less branched a;nd finally a lower row 

 or two of from ten to eighteen small simple conical papillae. The tentacle 

 sheaths are branched and somewhat similar to the dorsal papillae. The 

 dorsal papillae themselves are seven in number one each side getting 

 smaller and less dendriform from before backwards. The anal papilla 

 is a short truncated cone with a plicated opening lying between the 

 second and third papillae on the right side and slightly more towards 

 the median line. The small renal pore lies at its base. As customary 

 the genital aperture is situated below and just in front of the first papilla 

 and nearly always the penis is extruded upon fixation. 



Colour.— The colour of the body varies from a translucent greyish 

 white to quite a dark muddy colour and the arborescent papillae, while 

 the same colour at the base, become browner as they branch until 

 finally most of the tips are quite opaque, either a deep brown black or 

 pale chrome yellow. The body is not sharply marked ofif from the foot 

 but around the edge of the foot is a narrow line of opaque white which 

 starts at the edge of the veil. A similar white line frequently surrounds 

 the anal papilla. The papillae on the veil are also tipped for some dis- 

 tance with opaque white or pale chrome yellow. 



Dimensions. — ^Although a number of individuals of this species are 

 only of moderate size it may reach what is, for a nudibranch, enormous 

 dimensions. The largest specimen measured alive was 140 mm. long 

 by 43 mm. high by 33 mm. broad and after preservation it measured 

 114 by 36 by 28 mm. A preserved specimen in the laboratory obtained 

 by Dr. C. M. Fraser in 1913 measures 210 mm. long by 84 mm. high by 

 55 mm. wide. Allowing for approximately the same amount of shrinkage 

 this must have reached the size of almost 260 mm. long by 100 mm. 

 high and 65 mm. broad. 



Head. — ^The head is moderately large, not sharply marked off from 

 the sides of the body but distinct from the foot. The mouth appears as 

 a longitudinal slit. Sometimes on killing, the pharynx is excerted 

 showing the edges of the brownish yellow jaws. 



Foot. — The foot is elongated and narrow rounded off anteriorly and 

 terminating posteriorly in a fairly sharp point. 



Rhinophores. — The conical cLavus of the rhinophore is perfoliate and 

 bears from 16-18 leaves which like those in D. arhorescens alternate in 



