RECENT BRACHIOPODA 263 



shelled specimens and the greatest variety of species of lingulids and 

 discinids are found in shales and sandstones, and, furthermore, that the 

 physical evidence of the deposits in which such occur is in harmony with 

 the character of the sediments and the present distribution of the littoral 

 and shore living inarticulates. On the other hand, it is not at all rare in 

 the older Paleozoic deposits to find lingulids and discinids in limestones 

 and dolomites, and when the specimens are large and thick shelled, even 

 though they occur in such organic deposits, they give unmistakable evi- 

 dence of very shallow-water conditions and a hint that the shore may not 

 have been very far away. Small and thinner shelled species are also fre- 

 quently seen in limestones and shales, but the associated animals and the 

 character of the strata demonstrate that these also are shallow-water 

 forms. On the other hand, in black shale deposits (Utica, Marcellus, 

 Genesee), and more rarely in thin zones of black limestones (Marcellus, 

 Genesee) is frequently seen an abundance of very small and even minute 

 species of obolids, lingulids, and discinids that could not have lived on 

 the bottom of these "Black Seas" with their carbonaceous or even sul- 

 phurous depths. Nor can their size and frailty be taken as evidence for 

 deep-sea deposits, for they are manifestly of the surficial waters of a sar- 

 gasso-like sea, where in all probability they lived attached to floating 

 algge. In such deposits the evidence of the associated animals is that 

 they are either floaters (graptolites, or spore cases of algge), or swimmers 

 (pteropods as Styliolina, cephalopods as Endoceras, nautilids and gonia- 

 tids), or commensal floaters anchored to other suspended organisms as 

 the byssally attached thin shelled and modified bivalves described by 

 Clarke from the Genesee of 'New York. 



It is also desirable to point out here the wonderful vitality of the living 

 inarticulate brachiopods. Lingula is exposed on the tidal flats of Japan 

 for hours without injury, and on account of its accessibility is regularly 

 gathered by the poorer people for food. At high tide these animals are 

 covered with 3 to 4 feet of water. Their habitat may be brackish or foul 

 with decomposing organic matter, even to such an extent that all other 

 shell fish may be killed off, but Lingula will continue to live under such 

 adverse conditions. Yatsu, who has studied living Lingula, tells us that 

 on little estuaries in certain bays of southern Japan their habitats may 

 be covered by sand and mud brought down by stream freshets, so that all 

 of the burrowing shell fish will be destroyed, but Lingula will still live 

 in such stinking places and the individuals tunnel themselves to the sur- 

 face. The burrows are from 2 to 12 inches long, and the movements of 

 the animals up and down in the holes are made by means of the highly 

 contractile and regenerative peduncle. It is thought that Lingula may 



