260 CONFERENCE ON PALEOZOIC PALEOGEOGRAPHY 



Bathymetric Eange . 



in general 



The bathymetric range of the 158 species is as follows : 



Five, or 3 per cent, are restricted to the strand-line (3 Inarticulata, 2 

 Articulata) . 



Forty-four, or 28 per cent, range from the strand to about 90 feet (21 

 Inarticulata, 23 Articulata). 



Sixty-three, or 40 per cent, range from 90 to 600 feet (7 Inarticulata, 

 56 Articulata). 



From the strand to 600 feet occur nearly 71 per cent of the living 

 brachiopods, or 112 forms. 



Seventeen, or 10 per cent, range from 600 to 1,000 feet (all Articu- 

 lata) . 



Eleven, or 7 per cent, are deep-water forms below 1,000 feet, but adja- 

 cent to continents (all Articulata). 



Eighteen, or 11 per cent, are deep-sea forms situated near continents 

 (1 Inarticulata, 17 Articulata). 



Of typical deep-sea mid-oceanic forms ranging from 200 to 2,465 

 fathoms there are 5. 



Of the 158 recent species, at least 10 are practically restricted to the 

 area between tides. These are Laqueus ( ?) aleuticus, Magellania ffaves- 

 cens (goes down to 14 fathoms), Megerlina davidsoni (in an extinct vol- 

 canic crater), M. lamarchiana (goes in deeper water), an uncertain 

 species of Terehratalia (?) radiata, Lingula anatina (there are probably 

 other species of this genus), Discina striata, Discinisca cumingi (down 

 to 8 fathoms), D. lamellosa (to 10), and D. strigata. 



Between low-water mark and above 90 feet of depth the great majority 

 of inarticulate brachiopods live, or 21 species out of a total of 29 (Lin- 

 gula, 11; Glottidia, 4; Discina, 1; Discinisca, 4; and Crania, 1). Of 

 the articulate brachiopods, 23 out of the 129 live in these shallow waters, 

 and of those but 7 continue their range below 100 fathoms (Bouchardia, 

 1 ; Dallina, 1 ; Dyscolia, 1 — goes down to 250 fathoms ; Frenulina, 1 ; 

 Gw3^nia, 1 — goes down to 2,000 ; Kraussina, 1 ; Laqueus, 3 ; Liothyrina, 

 1 down to 600, 1 down to 1,300; Macandrevia, 1 down to 1,400; Tere- 

 hratalia, 1 ; Terebratella, 6 — 1 down to 120, and Terebratulina, 4 — 1 

 down to 1,170). 



From 90 feet and down to 600 feet there appear (with one exception) 

 all the remaining species of inarticulate brachiopods, 7 in number (Dis- 

 cinisca, 1; Crania, 6). Of the articulate forms, 56 appear here for the 

 first time, and of these at least 23 continue into still deeper water (Agul- 



