242 M. Valenciennes on the Anatomy of Nautilus. 



cartilage. The pericardium has a most remarkable arrange- 

 ment. It is folded in such a manner as to form six pockets 

 or sacs about the heart, three on each side, each of which 

 opens at the base of the gills, two at the hinder gills. Through 

 these openings the pericardium has a free connexion with the 

 great respiratory cavity of the animal. Upon these sacs are 

 situated the spongy elevations, similar to those which Cuvier 

 discovered in Octopus, Owen has also delineated them, but 

 not plainly enough. Lastly, the examination of the head has 

 shown me that this is surrounded by eight arms, as in Octopus. 

 The two upper arms are broad and flat, and capable of ex- 

 pansion. They surround the shell on the side of the raised part 

 of the spirally- wound cone (the convexity of the last convolu- 

 tion but one), so that the black part on the mouth of the shell, 

 not far from the spire, supports the basis of the broader arms ; 

 when they spread over the shell they deposit upon it the 

 outer layer streaked with yellow, nearly in the same way as 

 the margins of the foot of the CyprecB form a layer which is 

 coloured different to that which the neck-band of the animal 

 deposits*. 1 consider the divisions which project on the arms 

 as organs similar to the suckers of the Octopus. The outer 

 arms have seventeen divisions [gaines), from which proceed 

 as many feelers (cirrhes). The two great and broad arms 

 have each only two divisions. The two arms nearest to the 

 mouth possess, the one thirteen, the other twelve suckers 

 {ventouses) or divisions. The animal is fastened to the shell 

 by two strong muscles, which are continued into the interior, 

 in order to support the funnel which is formed by the reverted 

 fold, which contains in the interior the tongue-shaped organ, 

 through which the entrance of the water into the respiratory 

 cavity is prevented when the animal moves about quickly in 

 the water. The Octopus needs no such provision, as it swims 

 backwards ; Sepia, which moves in an oblique direction, pos- 

 sesses only a rudiment. According to this, the Nautilus has as 

 many arms as an Octopus ; but they are differently shaped, 

 very short, and furnished with contractile feelers, which come 

 forth from divisions which take the place of the suckers, and 

 which have even been considered as arms. The tube, which 

 descends into the sipho, continues through all the convolu- 

 tions, even to the very innermost. It is fleshy and surrounded 

 by a calcareo-gelatinous membrane, which is excreted from the 

 tube itself. This tube cannot therefore enter into connexion 

 with, the interior of the cavities of the chambers ; these cavi- 



* [From this description it is evident that M. Valenciennes accedes to 

 Mr. Owen's view of the relative position of the animal of the Nautilus Pom- 

 pilius to its shell, which had been opposed by Mr. Gray and M. De Blain- 

 ville. — Ed.] 



