422 



MOLLUSCA. 



corresponding to the hectocotylized arm of Dibranchs. The corresponding part 

 of the right inner lobe carries four tentacles, and is called the antispadix (q). 



In addition to these tentacles 

 of the lobes, there are the 

 four ocular tentacles already 

 referred to. 



The funnel is a tube 

 with muscular walls lead- 

 ing into the mantle-cavity, 

 and often containing (in 

 Nautilus and most Deca- 

 pods) a valve which admits 

 of passage outwards only. 

 It is placed on the ven- 

 tral surface behind the 

 head, and is to be regarded 

 either as the entire foot 

 of the animal, or as the 

 epipodia, the rest of the 

 foot having been wrapped 

 round the head and frayed 

 out peripherally into the 

 arms or lobes.* The view 

 that the funnel represents 

 the whole foot is strongly 

 suggested by the arrange- 

 ment in Nautilus. In 

 this animal it consists of 

 two muscular lateral lobes 

 of the ventral surface just 

 behind the head, which 

 are rolled round one 

 another without fusion. 

 When these lobes, which 

 are of considerable size, 



FIG. 336. Oral surface of a male (A) and female 

 (E) specimen of Nautilus pompilius in the expanded 

 condition, one-third the natural size linear (from 

 Lankester, after Bourne), a the shell ; b the external 

 annular lobe carrying 19 tentacles on each side, and 

 anteriorly enlarged to form the hood (Fig. 337) ; c the 

 right and left inner lobes, each carrying 12 tentacles 

 in the female, and divided in the male into two parts ; 

 d the posterior inner lobe ; e the oral cone ; / the ten- 

 tacles of the outer annular lobe projecting from their 

 sheaths ; g the two anterior tentacles of this lobe 

 belonging to the hood ; i superior, k inferior ophthal- 

 mic tentacle ; I eye ; n lamellated organ on the pos- 

 terior inner lobe of the female ; m paired laminated 

 organ on each side of the posterior inner lobe of the 

 female ; o the funnel ; p spadix ; q antispadix. 



* The view that the arms represent a portion of the foot is not in our 

 opinion satisfactorily established. It rests largely upon the fact that the 

 nervous supply is derived from that portion of the central nervous system 

 which is supposed to represent the pedal ganglion of other Mollusca. But 

 this, as Graham Kerr has pointed out, is not a strong argument, for a main 

 reason for regarding that part of the central nervous system, from which the 

 brachial nerves arise, as pedal, is that the nerves to the arms arise from it. 

 As pointed out below, separate and distinct ganglia are not distinguishable 

 in the central nervous system of Cephalopoda. 



