190 PICTURESQUE SKETCHES 



The Ammonite, so greatly developed in the lias 

 seas, was scarcely less so during the whole of the 

 succeeding period, and the variety of form which it 

 exhibits is not less remarkable than the vast multi- 

 tude of the individuals preserved. This form is some- 

 times more perfectly preserved also in the rocks of 

 this period than in any others ; and one example, 

 in which the fragile termination of the aperture has 

 been handed down in a perfect state, is given in the 

 accompanying figure (fig. 71). But this tribe of Ce- 



phalopoda was then repre- 

 sented by another group 

 numbers of which also are 

 met with in the lias, and 

 to which the name Belemnite 

 has been applied ; and this, 

 taking the place of a more 

 highly organized animal of 



its class than even the nauti- 

 OOLITIC AMMONITE. lug flnd ammonite? has been 



sometimes perfectly embalmed. The structure of the 

 soft parts is indeed so beautifully shewn in that same 

 clayey bed from which the perfect ammonite has been 

 worked out (the Oxford clay), that the oolitic period 

 is the most proper for its final description, though the 

 animal has been already alluded to,* and is almost 

 equally characteristic, not only of the lias and oolites, 

 but also of the newer secondary deposits. 



The Belemnite has received its name from a pecu- 

 liar dart- shaped stony fossil which is not uncommon, 

 and which, under various local names (such as thun- 

 derbolt, devil's toe-nail, &c.), is familiar to most 



* See ante, p. 145 et seq. 



