458 



PETRIFACTIONS AND THEIR TEACHINGS. 



CHAP. V. 



,''' Viv .'' 'I "'t" : ' '''. ' 



The elegance and variety of form of the shells of the numerous fossil 

 Cephalopoda are beautifully exhibited in the series of Nautili, Ammo- 

 nites, &c. deposited in these Cases, which 

 comprises a large number of the British spe- 

 cies, arranged and named, with their respec- 

 tive geological habitats affixed. 



Our limits will not admit of special notice 

 of any of these specimens, with the exception 

 of some remarkable examples of two genera 

 of naked Cephalopoda, Belemnites and Be- 

 lemnoteuthis, in Table-case 3, which display 

 every part of the structure of these extinct 

 forms at present known. 



BELEMNITES. Lign. 99. Table-case 3. 

 The cylindrical or fusiform stones, termi- 

 nating in a point at one end and having 

 at the other a conical cavity, of a dark brown 

 colour, and of a radiated sparry structure in- 

 ternally, must be familiar to most of my 

 readers by the name of Belemnite, (see Lign. 

 99, c.). These stones are the fossil osselets 

 or internal support of an extinct type of 

 cephalopoda allied to the Sepiadge or Cuttle- 

 fish. In the more perfect specimens, a conical 

 chambered shell, called the phragmocone^ 

 composed of a series of shallow concave cells, 

 of a nacreous substance, and pierced by a si- 

 phunculus, occupies the cavity of the belem- 

 nite ; and it has recently been discovered that 

 this phragmocone extended to a considerable 

 length, and terminated at the basal or cephalic 

 end, in two long processes ; and that a horny 

 capsule or integument invested the belem- 

 nite and the phragmocone, so as to form 

 a receptacle in which the viscera of the 

 animal were probably contained. These struc- 

 tures are very rarely found in the same 

 specimen; but the very fine Belemnite in 

 the Case before us, (collected by MR. BUY, 

 of Chippenham, who is well known for his 

 skill and sagacity in discovering and deve- 

 loping fossils of this kind,) displays the 

 several parts very distinctly ; they con- 

 sist of, 



1. An external Capsule, which invested 

 the guard, or osselet (sepiostaire), and ex- 

 tending upwards, constituted the external 

 sheath of the receptacle. 



2. The Osselet, characterised by its fibrous 

 radiated structure, terminates distally in 



a solid rostrum or guard, (c,) which has an alveolus, or conical cavity, to 



LIGN. 99. 



BELEMNITES PUZOSIANUS; 

 OXFORD CLAY, CHRISTIAN 

 MALFORD, WILTS. 

 (i nat. size.) 



a, one of the basal processes of 

 the phragmocone. 



b, the phragmocone. 



c, the rostrum or guard of the 

 osselet, containing the apex 

 of the phragmocone in its 

 upper part. 



