BRACHIOPOD A—THOMSON. 
47 
THE ST. PAUL ISLAND DISTRICT. 
The St. Paul and Amsterdam Islands rise from a common base above the 1,000 
fathom line, and are united with the Kerguelen group by a submarine ridge, which has 
a broad top between the 1,500 and 2,000 fathoms lines, and for the most part is less 
than 1,500 fathoms below the surface. The following species are known :—• 
Liothyrina winteri Blochmann.—371 fathoms. 
Megedina davidsoni Velain.—Abundant at low water in the interior crater. 
Mergedina occurs elsewhere only in Australia, but is closely related to the South 
African Kraussince. A very slight elevation of the sea bottom would connect the group 
above the 1,000 fathoms line with the Kerguelen group, and a greater community of 
fauna is perhaps to be expected. The difference in latitude, amounting to about 10 
degrees, is, however, sufficient to account for the difference in the shallow water forms, 
even if former connections had existed. 
THE MARION ISLAND DISTRICT. 
The Marion Island District consists of a group of Islands all rising from an 
elongated east and west submarine elevation of less than 1,000 fathoms depth. It 
consists of Crozet, Possession, Prince Edward and Marion Islands, and is separated 
from the Kerguelen group by a submarine trough of more than 2,000 fathoms in depth, 
whereas the seas between Marion Island and South Africa are less deep than 2,000 
fathoms. The distance between Crozet and Kerguelen Island is only 625 nautical 
miles, and between the 1,000 fathom contours there is about 450 miles. The Marion 
Island group has usually been included farm ally with the Kerguelen group, but it seems 
desirable to separate them in order to call attention to the differences in their brachiopod 
faunas. 
From the Marion Island group the following species are known :—- 
Terehmtulina septentrionalis Davidson (? of Couthouy).—150 fathoms. 
Terebmtula moseleyi Davidson.—210 fathoms. 
Waldheimia kerguelensis Davidson.—150 fathoms. 
Platidia anomioides (Scacchi).—150 fathoms. 
The occurrence of Platidia in this southern station is surprising, and, if confirmed, 
becomes of profound significance. Before the recognition of the generic distinctness 
of Amphithyris one might have said that the beak characters and shape were so dis¬ 
tinctive that Davidson could hardly have been mistaken as to the genus. In view, 
however, of the fact that Davidson considered Amphithyris seminula a synonym of 
Platidia anomioides , the Marion Island specimens need re-examination. It is true that 
