-48 GEOLOGY. 



ornamentation. It was now the " reign of the Ammon- 

 ites ;" but they have long ago passed away, and the 

 only present representative of the class is the Nautilus 

 of the Southern Ocean. Some of these ancient Am- 

 monites were monsters, being even three feet in diame- 

 ter. On the left of Fig. 147 (p. 247) are three species. 

 On the right of the figure are the Belemuites, in different 

 degrees of preservation. These belong to the Cuttle-fish 

 tribe. At 7 is one with its crown of arms, with which 

 it took its prey. The animal probably sailed along with 

 its long, conical shell pointed downward, and now and 

 then rose quickly to grasp some fish swimming above it, 

 darting down to the bottom to devour it. Like the cut- 

 tle-fish of the present day, the Belemnite had an ink-bag, 

 and used it for the same purpose to discolor the water 

 to aid it in escaping from its enemies. From the ink- 

 bag of a Belemnite found at Lyme Regis, in England, a 

 pigment was obtained like that which is now prepared 

 from the cuttle-fish under the name of India ink. 



353. Ichthyosaurus. This animal, whose skeleton is 

 represented in Fig. 148, combined in itself the character- 



Fig. 148. 



istics of a porpoise, a fish, and a crocodile. Its large 

 head was pointed like that of a porpoise, and it had pad- 

 dles or flippers like the Porpoise family. It was like a 

 fish in having no neck, the head and body being contin- 

 uous in outline. It was also like a fish in the arrange- 

 ment of its spinal column. Its teeth and jaws were like 

 those of a crocodile. Its eye was very large, its socket 

 being eighteen inches in diameter. It was so construct- 

 ed that the animal could see equally well in and out of 

 the water. Its jaws were so long'that, when fully open- 

 ed, their extremities would be seven feet apart. It was, 



