BRACHIOPOD A—'THOMSON. 
41 
the north and Mid-Atlantic, off Coats Land, Antarctic, and in the Pacific Ocean at 
various stations around the enclosing coasts and near the middle, at depths of from 
200 to 2,645 fathoms. This great geographic range is no doubt due to the pelagic life 
of the larvae in the free-swimming stage. Terebratula wyvillei, which most probably 
does not possess a surface-living larvae, is found at depths of from 1,035 to 2,900 fathoms 
off South Australia and North Queensland, in the north-west Pacific, south-west of the 
Galapagos Islands, off Valparaiso and the west coast of Patagonia, and near the Falkland 
Islands. It is thus almost restricted to the Pacific, but appears to have spread eastwards 
into the South Atlantic, as Blochmann observed, and westward to the Southern Ocean 
south of Australia. This circum-Pacific distribution is in marked contrast to the more 
limited range of other Pacific species inhabiting shallower waters, and helps to support 
Blochmann’s contention that for the coastal species the deep waters form impassable 
barriers. 
There are a number of other southern forms inhabiting depths greater than 
1,000 fathoms in one or the other hemisphere, but which nevertheless are not found far 
away from the continental margins. Most of these occur on the Pacific coast of 
America, viz. :— 
Liothyrina clarJceana Dali, 1,175 fathoms, Gulf of Panama, and 2,035 fathoms, 
south-west of the Galapagos Islands. 
Macandrevia americana Dali, 1,672 fathoms, Gulf of Panama, and 122 fathoms, 
off the west coast of Patagonia. 
Macandrevia diamantina Dali, 1,175 fathoms, Gulf of Panama, 2,222 fathoms 
off Peru, and 1,410 fathoms off Coats Land, Antarctica. 
Waldheimia wyvillei Davidson, 2,160 fathoms off Valparaiso. 
Besides Macandrevia diamantina and Pelagodiscus atlanticus, two other deep-sea 
forms are recorded from the Antarctic Coast, viz., Liothyrella blochmanni (Jackson), 
and Hemithyris sp. Jackson, 1,410 fathoms off Coats Land. 
SOUTHERN GEOGRAPHICAL DISTRICTS. 
The map accompanying this report is designed to throw into relief the areas of 
sea-bottom above 1,000 fathoms, which may be taken as the approximate depth 
limiting the seaward extension of the coastal species. The map is based on Stieler’s 
Hand-atlas, which includes the results of the Valdivia and Gauss Expeditions, the map 
of the Antarctic published in “The Sub-Antarctic Islands of New Zealand,” and the 
maps published by the various Antarctic expeditions including that by which the 
specimens here described were obtained. The Australian Antarctic Expedition made 
a very valuable series of soundings and has greatly modified previous views as to the 
contour of the sea bottom south of Australia. Very many more soundings are necessary 
*20218—F Vol. IV, Part 3. 
