74 



OOLITE. 



FIG. 51. 



FIG. 52. 



Terebratula biplicata. 



FIG. 53. 



Limulus moluccanus 

 (recent). 



Ammonites Jasoni. 



and one to which the modern lobster and cray-fish belong. 

 Insects resembling the dragon-fly have been found in the 

 oolite. 



The deeper oolitic seas were occupied by various species of 

 terebratula, a brachiopodous mollusk remarkable as having lived 

 in one form or another from the earliest to the present time. 

 In the shallower seas were other bivalves. There was also 

 abundance of all the univalve classes, Pteropoda, Gasteropoda, 

 and Cephalopoda. In the last, we see an advance of cha- 

 racters among the ammonites and belemnites, which now appear 

 in many varieties. The Belemnite, which belonged to the 

 higher order of the class, those having only two branchiae, 

 calls for some particular notice. It is an elongated, conical 

 shell, terminatiDg in a point, and having, at the larger end, a 

 cavity for the residence of the animal, with a series of air- 

 chambers below. The animal, placed in the upper cavity, 

 sent its tentacula abroad over the summit of the shell, search- 

 ing the sea for prey. The creature had an ink bag with which 

 it could muddle the water around it, to protect itself from 

 more powerful animals, and, strange to say, this has been 

 found so well preserved, that an artist has used it in one 



