BRACHIOPODA. 497 



branches, and other submarine bodies. They inhabit all 

 seas. There are seventy-five living, and more than twelve 



Fig- 479- Fig. 480. 



Terebratula septentrionalis, Couthouy. 



Small specimen. New England and 

 Terebratula septentrionalis, Couth. northward 



Fig. 481. 



Lingula anatina, Lam. One half. Philippines. 



hundred fossil species. The principal families are Terre- 

 bratulidas, Spirulidae, Rhynchonellidae, Orthidae, Produc- 

 tidae, and Lingulidae. 



Mr. Edward S. Morse, in a paper published in the Es- 

 sex Institute Proceedings, entitled " Classification of the 

 Mollusca based on the Principle of Cephalization," claims 

 to have shown that what has been regarded as the dorsal 

 valve in Brachiopods is the ventral valve, and what has 

 heretofore been considered the posterior pole of the same 

 is^the anterior. 



SUB-SECTION IV. 



THE ORDER OF BRYOZOA, OR BRYOZOANS. 



THE Bryozoa also called Polyzoa are very small or 

 minute molltisks growing in clusters upon rocks, shells, 

 and sea-weeds, which they ornament with their delicate 

 ramifications. Some kinds, however, inhabit only fresh 

 waters. All are polyp-like in general appearance, -but 

 molluscan in structure. The aggregated cells of some 

 genera are coral or coral-like. 



F F 



