102 CUTTLE-FISH. BELEMNITE. SPIRULA. 



The body is thick and fleshy, contained in a kind 

 of bag, whence the head issues, surrounded by 

 these arms, which vary in different genera. 



'* The common cuttle-Jish, a native of our seas, 

 will give you an idea of a cephalopode. 



*' In the first family a fossil-shell occurs that 

 is very frequently met with. 



" Family, Orthocerata ; genus, Belemnite, 

 thunder-stone, or arrow-head. These fossil- 

 shells occur abundantly in the chalk formations. 

 Many superstitious notions have been attached to 

 this extinct marine animal : of these you will find 

 an acccount in the ' Penny Cyclopaedia." 



" In the family Lituolita we meet with the deli- 

 cate and remarkable little shell Spirula Peronii, 

 distinct from Nautilus by the separation of the 

 volutions : it is nearly covered by the body of the 

 animal. The colour is white ; the texture thin 

 and brittle : it has a lateral syphon, the orifice of 

 which is very clearly to be seen as each compart- 

 ment is taken off. There is but one species ; it 

 is found in the Southern Ocean and the Moluccas. 

 The shells are seen floating on the surface of the 

 water when the animal is dead, and are some- 

 times carried to the shore. (Plate 9.) 



" Another family of this order, Nantilacea, 

 contains, among many other genera, the cele- 

 brated Nautilus. This genus, you are already 

 informed, is distinguished from Argonauta by 



