yOUNG CEPHALOrOD WITH PEDUNCULATE EYE?. 313 



before us was a Gymnosomatous Pteropod. That notion was 

 further encouraged by the existence of only two arm-like pro- 

 cesses of the forefootj bearing suckers, these having, as must be 

 at once admitted, a strong resemblance to the sucker-bearing 

 arms of the Gymnosomatous Pteropod, Pneumodermon. 

 When once the mantle-flap and the subpallial chamber are over- 

 looked, it is natural to interpret the conical process marked /in 

 figs. 1 and 2 as the anus, and to conclude that the supposed 

 Pteropod has no representative of the mesopodium or " ptera." 

 In reality, however, the little creature is not a Pteropod, but one 

 of the Siphonopoda (the group to which the term Cephalopoda 

 is usually restricted). It is not gymnosomatous, but as shown 

 in fig. 2, it has the usual mantle-flap and subpallial chamber 

 characteristic of the cuttle-fishes. The supposed anal cone 

 (figs. 1 and 2,/) is in reality the funnel or siphon, and the true 

 anus is placed within the subpallial chamber near the spiral 

 mass of pigment noted by Suhm (figs. 1 and 2, g). 



The rolling up of the two lateral growths of the mesopodium 

 to form a funnel or siphon is the absolute and distinctive race- 

 mark of the Siphonopoda or Cephalopoda seusu restricto. 

 There can therefore be no further doubt about the affinities of 

 Suhm^s organism. At the same time I may point out a few 

 additional characteristics which it presents, and are only to be 

 found among the cuttle-fishes. 



(1) Near the anus (g) is a spiral mass of black pigment. This 

 is the secretion of the ink- sac seen through the walls of that 

 sac. The spiral form of its lumen is characteristic. The ink- 

 sac is distinctively characteristic of the Dibranchiata. 



(2) A number of cliromatophor-cells, exactly resembling 

 those of young Loligo, are scattered over the surface of the 

 body in the integument (fig. 2, h). Only Dibranchiata are known 

 to have chromatophors of this particular form and appearance. 



(3) There is (as Suhm observed, but could not persuade 

 himself to believe) a very delicate (probably horny) "pen" 

 sunk beneath the integument of the antero-dorsal surface (see 

 woodcut, fig. 2, i). Such a pen exists only in the Dibranchiate 

 Siphonopoda. 



