350 



are marine, and their bathymetric distribution ranges from 

 the shore zone, where they are exposed at low tide, to the 

 abyssal depths, a species of Bifaxia having been obtained 

 below 3,000 fathoms. The majority of species, however. 

 live in moderate depths. While the Bryozoa normally lead a 

 strictly sedentary benthonic life, a few species may drift 

 about with the seaweed to which the}^ are attached, thus 

 assuming a pseudo-planktonic habit. 



The egg of the bryozoan develops into a mero-plank- 

 tonic, ciliated larva, which later on settles down, becomes 

 attached, and develops into a full-grown individual, which, 

 by budding, produces the colony. 



Brachiopoda. — The Brachiopoda are marine benthonic 

 organisms, of exceptional stratigraphic importance, since 

 they are to a high degree dependent on the facies of the sea 

 bottom. While typically marine, some species can become 

 adapted to brackish and even fresh water. Thus Davidson* 

 states that at Trias Cove whole colonies of Terebratulina 

 septentrionalis were discovered on stony bottom in clear 

 fresh water. Some species of Terebratula and Lingula can 

 withstand .a considerable exposure, the former having been 

 noted out of water for hours together at low tide. Lingula 

 is buried, by means of its long fleshy peduncle, in the sand 

 near shore; Crania is attached to rocks and shells by its 

 shell; while the majority of bachiopods are attached by 

 their fleshy pedicles to rocks, shells, corals, or to one an- 

 other. They seldom live on muddy or sand}' bottoms, but 

 are readily embedded in these, by becoming detached after 

 death from the rocks or other objects to which they adhered. 



The bathymetric distribution of the Brachiopoda ranges 

 from shallow water to 2,900 fathoms (in one case), the 

 majority of species occurring above the hundred fathom line, 

 while quite a number have been obtained in depths of ten 

 fathoms or less. A number of species have an individual 

 range of several hundred fathoms, this range in one or two 

 cases being nearly 800 fathoms. 



* Mon. Rec. Brach., I., p. 28. 



