766 FUNNEL AND CAPITO-PEDAL CARTILAGE. 



Cephalopoda as a mucus-gland, and has further homologised it with the pedal gland of the 

 Gastropoda. 



After comparing the figures published by Jatta, relating to the funnel-organ of 

 Sepia officinalis, Octopus vulgaris and other species, I have no doubt that the funnel- 

 gland of Nautilus is an organ homologous with the corresponding structure in the funnel 

 of other Cephalopoda. I have not made sections through this gland, and shall have no 

 further opportunity of doing so, but I have really no hesitation in the matter notwith- 

 standing this omission (cf. PI. LXXVI. fig. 1). 



The funnel-organ of Nautilus passes laterally into the alae infundibuli. and posteriorly 

 it is attached to the ventral surface of the skin covering the shell-muscles by an elongated 

 limbus. I observed a network of what I took to be venous channels below the mucosa 

 of the funnel-organ, and two large veins passing from the limbus into the vena cava. 

 (See figures on PL LXXXII. and LXXXIII.) 



The cartilage forms a very incomplete wall to the endochondral sinus, only the ventral 

 and lateral sides being bounded by massive cartilage, while dorsally there is a narrow bar 

 of cartilage (arcus cartilaginis) which forms two bosses projecting into the peristomial 

 haemocoel between the pedal and visceral commissures. Between the arcus and the pedal 

 commissure are to be seen two orifices which represent main conduits leading from the 

 peristomial haemocoel to the endochondral sinus (PL LXXXII.). Behind the arcus occurs 

 the insertion of the inferior retractor muscles of the buccal cone into the body of the 

 cartilage on each side. 



The infundibular nerves arise from the pedal commissure and run straight forwards 

 into the crura infundibuli dorsad and ectad of the tubular sinuses, in which the above- 

 mentioned levator muscles lie. Their topography will be elucidated in the chapter on 

 the peristomial haemocoel. 



In concluding the present chapter, I should like to emphasize the view that the 

 capito-pedal cartilage of Nautilus is to a large extent a funnel-cartilage, and is probably 

 not directly homologous with the cephalic cartilage of Dibranchs, but related to the 

 latter through substitution. It is of course obvious that the principle of substitution is 

 apt to become little more than a form of words, and to convey no true image to the mind. 

 In regard to the endoskeleton of Cephalopoda the idea which is present to my mind is 

 the following. The cephalic cartilage is to the Dibranchs what the capito-pedal cartilage 

 is to Nautilus, but the former is not to be identified with the latter, and does not 

 merely represent a specialisation of it. If this be so we might expect to find traces 

 of a true capito-pedal or funnel-cartilage in the Dibranchs, and indeed a pah- of siphonal 

 cartilages 1 curiously recalling the cornua of the cartilage of Nautilus, has been discovered 

 by Hoyle 2 in the remarkable and, in more than one sense, primitive genus Gonatus. 

 Without venturing to express the definite opinion that these apparently rudimentary 

 siphonal cartilages of Gonatus may represent vestiges of a capito-pedal cartilage such as 

 occurs in the still more primitive genus Nautilus, I think the suggestion may be one 

 worthy of the attention of teuthologists, although the fact that they occur in the ventral 



1 The funnel of Cephalopoda is often quite properly called the siphon but the latter term is also quite 

 improperly applied to the siphuncle of Tetrabranchiates, and for this reason I have avoided its use. 



- Hoyle, W. E., "Observations on Gonatus fabricii," op. tit., see p. 120. Cf. also on Gonatus, the 



same author's Report on the Cephalopoda collected by H.M.S. Challenger, 1886, p. 173. 



