AMMONITES. 



31 



— 



probably serves 

 the animal in 

 crawling. The 

 tentacula, which 

 are inserted near 

 the mouth, are 

 not furnished 

 with cups as in 

 the p re c e d i n g 

 family : they are 

 retractile and in 

 considerable 

 number. The 

 eyes are pedun- 

 culate, that is, 

 supported on a 

 feort of foot-stalk 

 or stem : there 

 is no organ of 

 hearing, nor 

 pouch, nor fins, 

 and the branchiae 

 are four in num- 



^gj.^ Fig. 16.— NAUTILUS. 



26. A great number of shells are found in the fossil state 

 which are very analogous in structure to the nautilus, and which 

 probably belonged to cephalopods of similar conformation ; they 

 are the Ammonites {Jig. 17), vulgarly called Horns of Ammon, 

 in consequence of the resemblance of 

 their volutes or whorls to those of a 

 ram's horn. These animals were 

 among the most ancient inhabitants of 

 the earth and lived in every sea. Their 

 remains abound in the secondary for- 

 mations (See Geology), and are met 

 with in all parts of the world ; but they 

 have long since disappeared from the 

 surface of the earth, and in those lay- 

 ers which rest upon the chalk, not 



Fig. 17.-AMM0NITE. gyg^ ^ ^j.^^g Qf. tj^g^ ig ^Q^^j^ Coj^g^,. 



quently, their destruction must have occurred at a period long 



Explanation of Fig. 16. — The nautilus shell opened : — t. the tentacula ; — 

 €. the funnel or reservoir ; — p. the foot ; — m. part of the mantle ; — o. the eye ; 

 — s. the syphon. 



26. What are ammonites ? Where are they found ? 



