150 



ANIMAL KINGDOM. 



The articulations are made in the hardened skin, and not, as in 

 Vertebrates, in internal bones ; and the principal nervous cord 



Figs. 160-168. 



60, 



Mollusks, figs. 160-168. — 1. Brachiopods: 160, Terebratula impressa, of the Oolite; 161 

 Lingula, on its stem. 2. Bryozoa: 162 (X 8), 162 a, genus Eschara. 3. Conchifers, or 

 Common Bivalves: 163, 164; 165, the Oyster. 4. Gasteropods : 166, Helix. 5. Pteropods: 

 167, genus Cleodora. 6. Cephalopods: 168, Nautilus (X }Q- 



Fig. 169. 



The Calamary or Squid, Loligo vulgaris (length of body, 6 to 12 inches) ; i, the duct by 

 which the ink is thrown out ; p, the " pen." 



passes below the stomach and intestine, and has usually a ganglion 

 in each segment of the body, — so that the articulate structure is in- 

 dicated by the nervous system as well as by the joints of the body and 

 its members. The fundamental element of the body is, hence, a 

 segment or ring containing a nervous ganglion and a portion of the 

 viscera. In some worms the segments are so far independent that 

 the animals multiply by spontaneous fission. 



