CEPHALOPODA. 443 



tinue to designate by their ordinary name, vela, expand into 

 broad membranes (b). 



M. Sander Rang, who, during a residence at Algiers, had ample 

 opportunity of studying the living Argonaut, ascertained that in the 

 figure copied from Poli, which we have given in a preceding page, 

 the animal is placed in its shell in a reversed position ; and that, 

 when alive, the creature is always found with its veliferous arms 

 turned towards the spire of its shell, instead of in the opposite 

 direction, as represented in the drawing referred to. Moreover, 

 the vela, instead of forming sails, are invariably tightly spread 

 out over the external surface of the shell (Jig. 207), which they 

 cover and entirely conceal from view. With its veliferous arms 

 thus firmly embracing its abode, the Argonaut has two modes 

 of progression. It can certainly raise itself from the bottom, and 

 sport about at the surface of the water ; but this is simply effected 

 by the ordinary means used by Calamaries and Cephalopods in 

 general, namely, by admitting the sea-water into its body and then 

 ejecting it in forcible streams from its funnel, so as to produce a 

 retrograde motion, which is sometimes very rapid. Its usual 

 movements are, however, confined to crawling at the bottom with 

 its head downwards ; and in this way it creeps, carrying its shell 

 upon its back. 



The reader will obtain a better idea of the real appearance of 

 the Argonaut in its shell by inspecting the annexed copy of 

 M. Ranges figure than from any verbal description, and we borrow 

 that gentleman's own account of its general appearance.* The 

 membranous portions of the expanded arms, dilated beyond any- 

 thing we could have pictured to ourselves while knowing the 

 animal merely by specimens preserved in spirits of wine, are 

 spread over the two lateral surfaces of the shell in such a manner 

 as to cover it completely from the base of the hard edge to the 

 anterior extremity of the edge of the opening, and consequently 

 the keel. The application of these membranes is direct, and with- 

 out any puckering or irregularity whatever : the lower part of the 

 two large arms being completely stretched, so as to form a kind of 

 bridge over the cavity left between the back of the mollusk and 

 the retreating portion of the spire. When the mollusk contracts 

 itself, it frequently draws in more or less completely its large arms 



* For more ample details upon this subject, the reader is referred to an excellent 

 translation of M. Rang's paper contained in Mr. Charlesworth's Magazine of Natural 

 History. New Series, vol. iii. 



