274 CONFERENCE ON PALEOZOIC PALEOGEOGRAPHY 



L. uva (widely distributed from Tehuantepec to Cape Horn and South 

 Georgia) has crept north in the Atlantic as far as Buenos Aires, and with 

 the breaking down of Gondwana, L. cubensis, an Antillean species here 

 of wide distribution, has maintained itself with modification on Ascension 

 as a relict, but is now recognizable, according to Blochmann, as a distinct 

 geographic variant. Another associ^ed relict here is TerehratuUna caih 

 leti. In regard to the remarkable distribution of the 3 closely allied 

 forms of Liothyrina {L. spkenoidea in Lusitanian region, L. cubensis in 

 Antillean, and the Ascension unnamed form), Blochmann (1906, page 

 701) states the following: "The 3 forms are the descendants of one that 

 was bound to the shores of the central Mediterranean, which was extant 

 up to Tertiary time, and since then the stock has been broken into the 3 

 discontinuous areas. Ascension we must regard as a part of the north 

 shore of the land-bridge that once united Africa with South America." 



Chlidonophora, — This deep-sea genus had its origin along the north 

 shore of Gondwana, and C. incerta is found off Havana to the northwest 

 of Trinidad and in the equatorial mid- Atlantic. The other form occurs 

 in the Indian Ocean off the Maldives and Laccadives. The spread was 

 through ancient Tethys. 



Macandrevia.—It& most typical development (M. cranium) is now off 

 the coast of Norway, spreading thence to North Cape and Greenland, 

 east coast of North America at great depths, and south off Europe into 

 the Mediterranean area. M. tenera occurs in Davis Strait, but there is 

 no representation now in the Antillean region. In the Pacific, in the 

 Gulf of Panama, 3 species occur, and 2 of these are also known in the 

 deeps off Chile and Peru. Eecently Blochmann has described a final 

 species from the Antarctic Kaiser Wilhelm Land. 



EQUATORIAL ATLANTIC 



There is a great dearth of brachiopods in the equatorial Atlantic be- 

 tween 10 degrees north and 30 degrees south latitude. But a single shal- 

 low-water species is restricted to this great region. This is Discina 

 striata, found in the littoral at Cape Palmas, Africa, and may be of 

 Mediterranean origin. The few other brachiopods of this region are 

 either northern relicts (2) of broken Gondwana, or deep-sea migrants 

 (2), or shallow-water migrants from the Antillean regions (2). On 

 Ascension, in mid-Atlantic, are found the relicts Liothyrina cubensis ? 

 (now changed into another form according to Blochmann) and Tere- 

 hratuUna cailleti (also off northern Brazil). The only other northern 

 migrant along the eastern shore of South America is the Antillean Cis- 



