MOLLUSCA. 439 



stalks. In the specimens of the Ocyihoe Cranchii, procu- 

 red during the expedition to the Congo, Dr LEACH observ- 

 ed " four oblong spots on the inside of the tube, resembling 

 the surfaces for the secretion of mucus, two inferior and la- 

 teral, and two superior, larger, and meeting anteriorly. On 

 the rim of the sac, immediately above the branchiae, on 

 each side, is a small, short, fleshy tubercle, which fits into 

 an excavation on the opposite side of the sac."" Phil 

 Trans. 1817. 



This animal was long considered as the fabricator of the 

 shell termed Argonauta or Paper Nautilus. The observa- 

 tions, however, of Mr CRANCH, the Zoologist to the Con- 

 go Expedition, have demonstrated that the shell is merely 

 the temporary residence of this animal, which it quits at 

 pleasure. The body of the animal does not conform in 

 shape to the cavity of the shell, nor to all its irregularities 

 of surface ; neither is there any muscular attachment be- 

 tween them. " On the 13th of June" (says Dr LEACH, 

 when publishing the notes of Mr CRANCH), " he placed 

 two living specimens in a vessel of sea- water ; the animals 

 very soon protruded their arms, and swam on and below 

 the surface, having all the actions of the common Polypus 

 (octopus) of our seas ; by means of their suckers, they ad- 

 hered firmly to any substance with which they came in con- 

 tact, and when sticking to the sides of the basin, the shell 

 might easily be withdrawn from the animal. They had 

 the power of completely withdrawing within the shell, and 

 of leaving it entirely : One individual quitted its shell and 

 lived several hours swimming about, and showed no incli- 

 nation to return into it; and others left the shells as he 

 was taking them up in the net. They changed colour, 

 like other animals of the class Cephalopoda ; when at rest, 

 the colour was pale flesh-coloured, more or less speckled 

 with purplish ; the under parts of the arms were bluish- 



