13RACHI0P0DA—THOMSON. 
55 
The Australian Recent fauna, leaving aside the subtropical elements on the 
northern parts of the east coast, must be similarly regarded as a remnant of the Miocene 
fauna of that area. The only genera which have not been determined fossil are Gryptopora, 
Aetheia (fossil in New Zealand and South America), Argrotheca (fossil in New Zealand), 
Kmussina , and Campages, most of them small forms which may easily be overlooked. 
As in the case of New Zealand, Pliocene or Post-Pliocene migrations from other southern 
areas are unnecessary from a consideration of the brachiopod fauna. 
The South American Recent fauna is also in great part generically similar to the 
Miocene faunas of that continent, the most important exceptions being Liothyrella , 
which is unknown fossil in that area, although it is not a genus that could easily be over¬ 
looked, and Macandrevia which has not been recorded fossil anywhere in the southern 
hemisphere. Yon Ihering points out also that Magellania venosa has no ancestral 
form in the Patagonian Miocene, and considers it a Recent immigrant in the Magellan 
district from Chile, where the related form Magellania fontanel occurs fossil. This 
appears probable enough as Macandrevia must certainly be considered a recent immigrant 
from the North Pacific, but it should be noticed that Magellania fontanei has since 
been recorded from the Antarctic Oligocene-Miocene. 
The Antarctic Recent fauna is the least like the Tertiary fauna of the same district 
owing to the presence, on the one hand, of the recent northern immigrants Macandrevia 
and Frieleia, and on the other species of Magellania s. str., a genus apparently confined 
in the Miocene to Australia. The absence of this genus in New Zealand and its presence 
in the Macquarie Islands seems to point to a former bridge connecting Tasmania with 
the Antarctic through the Macquarie Islands. Too much stress must not be laid on 
this genus, however, for even with the narrow restriction that it has undergone it may 
still be polyphyletic. There is nothing to prevent any species of Terebratella attaining 
Magellaniform loop characters by simple absorption of the jugal band, and Terebratella 
s. str. had already spread to South America, New Zealand, and Australia by the Oligocene- 
Miocene. On the whole, then, it appears that in the districts from which Oligocene- 
Miocene faunas are known, the recent faunas are descendants of those fossil faunas, 
and the only connection which is made likely by the Recent brachiopod fauna is one 
between South America and the Antarctic. Even this is not definitely demanded, for 
the genus Macandrevia is one which can live below the 1,000 fathom line, and although 
the South American species and two of the Antarctic species have so far only been found 
in much shallower waters, the first mentioned, M. americana, also occurs in the Gulf 
of Panama in 1,672 fathoms, while M. diamantina is found at a depth of 1,410 fathoms 
in the Antarctic and 1,175 fathoms in the Gulf of Panama. 
The elements of the southern faunas which can be definitely considered as descen¬ 
dants of the southern Oligocene-Miocene faunas are :— Crania, Hemithyris, Aetheia, 
Murravia, Terebratulina, Liothyrella, Argyrotheca, Megerlina, Aldingia, Bouchardia, 
Magadina, Gyrothyris, Stethothyris, Neothyris, Terebratella and Magellania. Of these 
