268 CONFERENCE ON PALEOZOIC PALEOGEOGRAPHY 



Of the 158 living brachiopods but 25, or about 16 per cent, are also 

 found fossil. None are older than the Eocene (Megathyris decoUata) ; 

 of the Miocene there are 4 additional species (Dallina septigera, Platidia 

 anomioides, TerehratuUna caput serpentis, and Thecidium mediterra- 

 neum). From the Pliocene there are 15 (Cistella cuneata, Crania ano- 

 mala, C. turhinata, Glottidia aTbida, Hemithyris nigricans, H. psittacea, 

 Liothyrina affinis, L. splienoidea, L. vitrea, Macandrevia cranium, Muhl- 

 feldtia ecliinata, M. truncata, Platidia davidsoni, Terebratella dorsata, 

 and Thecidium barretti) ; of the Pleistocene 5 (Cistella cistellula, Dal- 

 lina ( ?) spitzhergensis, Gwynia capsula, Magellania lenticularis, and 

 Miihlfeldtia monstruosa) . 



Geographic situation of recent Brachiopods 

 in general 



All brachiopods without exception live in marine waters, and in the 

 main their habitats are in the shallower waters bordering the continental 

 masses. This is very clearly brought out in the "Chart of the world 

 showing the distribution of the Eecent Brachiopoda/' by Hall and 

 Clarke (1894, chart facing page 148), and in another by Blochmann 

 (1908, plate 40), giving the distribution of the Liothyrinse. These 

 maps also show that but very few species have strayed far away from 

 the continents in the truly abyssal regions. Only 5 have permanently 

 adapted themselves to the great oceanic areas {Pelagpdiscus atlanticus, 

 Hemithyris strebli, Chlidonophora chuni, C. incerta, and Liothyrina ( ?) 

 wyvillii). With these should be considered 13 other forms which also 

 inhabit great depths, but whose situation remains adjacent to the conti- 

 nents (see list on page 6). Then there are 11 species living perma- 

 nently below 1,000 feet that may be spoken of as deep-water forms, but 

 they are not as yet deep-sea animals, because their habitats are in con- 

 nection with the continental shelves (see list on page 5). In other 

 words, but 3 per cent of living brachiopods have permanently left the 

 continental waters, a further 8 per cent are transitional between the 

 abyss and the continental shelves, and an additional 7 per cent are still 

 attached to the shallower waters of the outer parts of the continental 

 shelves. This bathymetric distribution may be stated in still another 

 way, namely, 81 per cent of living brachiopods are bound to the shallow 

 waters bordering the land masses, 7 per cent are in the deeper waters of 

 the continental shelves, 8 per cent are transitional to the oceanic areas, 

 and 3 per cent are permanent inhabitants of the vast and cold Neptunic 

 underworld. 



