CEPHALOPODA 



291 



In addition to the foot proper, whose edges constitute the circum- 

 oral appendages, the Cephalopoda possess an epipodium which is well 

 developed, but highly specialised to form a funnel. The epipodial 

 nature of the funnel may be specially well seen in young embryos 

 (Figs. 257, fu ; 1 19, D, fu), in which this organ is situated laterally 

 and posteriorly, between the mantle and the foot. Primitively the 

 funnel has the form of two symmetrical lateral lobes, which simply 

 incline towards one another and overlap in Nautilus (Fig. 276). 

 In the Dibranchia, however, these two lobes become fused together 

 during development (Fig. 290, (9) q) and form a complete tube 

 projecting beyond the pallial cavity (Figs. 253 and 258, etc., fu). 

 Through this tube the excrements, the secretion of the ink-sac, and 

 the generative products are ejected. The interior of the funnel 

 is generally provided with a larger 

 or smaller valve, attached to its 

 anterior or dorsal face ; as, for 

 instance, in the Nautilidae (Fig. 

 276, b) and the majority of the 

 Decapoda (Fig. 259, fu) ;* but this 

 structure is absent in Leachia 

 among the Oigopsida and in the 

 Octopoda. In addition, the in- 



Fro. 257. 



Young embryo of Sepia offidnoiis, 

 viewed from the dorsal side, a, anus ; 

 e > e ye ; /, funnel ; gi, gill ; m, mouth ; 

 of, otocyst ; pa, mantle and shell ; vi, 

 vitellus ; 1, 2, 3, 4, 5, arms. (After 

 Kolliker.) 



fi" 



FIG. 258. 



Grimalditeuthis richardi, ventral as- 

 pect, a, aims ; c, left eye ; fi', anterior 

 lin ; fi", posterior tin ; fu, funnel. (After 

 Joubin.) 



ternal wall of the funnel is furnished with an epithelial outgrowth 

 of variable form, constituting a mucous gland called Muller's 

 organ. 



Powerful muscular bundles, originating from the cephalopedal 

 mass and from the sides of the funnel, unite together and are inserted 

 symmetrically on the sides of the shell (Fig. 272, m). In Nautilus 

 they are inserted on the interior of the shell, in the Dibranchia on 

 its external surface, in Spirula on the margins of the last chamber. 



