202 J. GRAHAM KERR. 



In Nautilus the arrangement of the circumoral lobes and 

 tentacles has been described by Bourne and by Lankester, so 

 that it is unnecessary to go into details. Anteriorly (dorsally) 

 is the large fibrous mass of tissue which forms the hood. 

 Laterally, on each side, is an aggregation of tentacles. Anteriorly 

 (dorsally) the mass of tentacle-sheaths is directly continuous 

 with the hood. On slicing away the substance of the hood 

 carefully, it is seen that the bases of all the outer tentacles are 

 embedded in it. The appearance of tentacle-sheaths is due 

 merely to the more or less distinct marking off by superficial 

 grooves of the parts of the mass surrounding each tentacle. 

 Hood and tentacle-sheaths together form a perfectly continuous 

 mass lying anterior (dorsal) to the buccal mass and cuiTing 

 backwards (downwards) on either side of it in saddle-like 

 fashion. In the male this is very obvious, the two limbs of the 

 mass being connected together posteriorly merely by a thin 

 shelf In the female, however, this bears on its inner side the 

 "inferior inner lobe," which bears on each side a group of 

 tentacles and whose appearance suggests a bilateral origin. 

 The main impression given by the tentacle-hood complex is 

 that of a saddle-shaped structure, situated anterior (dorsal) to 

 the buccal mass — its limbs passing backwards on either side of 

 the latter. The anterior (dorsal) part of the complex here 

 predominates : it is developed less equally all round the buccal 

 mass than in Decapods ; its preponderating part is dorsal. 



The next point of interest in the gross anatomical relations 

 of the parts lies in the funnel which, according to the upholders 

 of the "pedal" view, is primitively continuous with the tentacle- 

 hood mass. 



The Funnel. — This is a large tongue-shaped structure 

 attached to the posterior face of the body — to the roof of the 

 mantle-cavity, into which it imperceptibly passes aborally. At 

 its oral end it projects parallel to the axis of the buccal mass — 

 quite free and separated by a deep groove from the hood and 

 tentacle-mass. Tongue-like in form, its margins are inrolled 

 about a longitudinal axis, so that one comes to overlap the 

 other. Which does so appears to be quite inconstant in dif- 



