1912.] NATURAL SCIENCES OF PHILADELPHIA. 133 



North American species of that horizon, Venericardia planicosta, 

 Latirus tortilis, Calyptraphorus velatus, var. compressus, Levifusus 

 pagoda, and Turritella mortoni. To add to the interest, mingled 

 with these were the characteristic Brazilian species from the Pernam- 

 buco beds, Callista mcgrathiana, Chione paraensis, and Cucullcea 

 harttii. These had been previously found only in the Brazilian 

 beds, especially in those of the Maria Farinha, a rivulet near Pernam- 

 buco. Thus the age of the Maria Farinha beds which before were, 

 usually doubtfully referred to the Cretaceous, and that of the Soldado 

 No. 2 bed was definitely established as equivalent to the Eocene of 

 Midway, Alabama. 



The Soldado fauna was rich and varied. The genera Ostrea, 

 Venericardia, Fusus, and Turritella led as regards numbers of species. 

 By the discovery of Venericardia planicosta at Soldado, its already 

 remarkable range is extended south as far as 10° N. Lat. Moreover, 

 its Antillean centre of distribution, postulated by Dr. Dall in 1903, 

 is now established by the facts. In the light of those facts, we can 

 trace this species from northern South America to southern and 

 western North America and to northern and southern Europe. 



From the Pernambuco basin the Cucullwa harttii fauna travelled 

 north as far as Soldado; for in the early Tertiary there was no 

 Amazon to act as a barrier with its discharge of fresh water. As far 

 as known, Soldado was the northern limit of the migration of this 

 fauna. 



The Venericardia planicosta fauna travelled from the Soldado to 

 the Alabama basin. This wandering species also crossed the strait 

 covering the future Isthmus and established colonies along the 

 Pacific coast in California and Oregon. It is a curious fact that its 

 descendants are living there to the present day, although elsewhere 

 the group has been entirely blotted out. 



From the Alabama basin the Venericardia plan icosta fauna continues 

 to advance in a northeasterly direction up the coast, the peninsula 

 of Florida having not yet been raised to force a detour. The accom- 

 panying species settled down along the way, Turritella mortoni 

 advancing as far as Maryland. Thence Venericardia planicosta 

 continued its advance alone to the north and east, eventually reaching 

 the shores of northern Europe, probably via a Greenland-Iceland 

 shallow water route. Established in Europe, it spread in great force 

 over Belgium, France, and northern Italy. 



In Bed No. 8, Soldado Rock, one of the commonest species is 

 Ostrea thirsce, so characteristic of the Lignitic Eocene of Alabama. 

 Hence this species indicates a later migration from South to North 

 America. 



In conclusion, we may list the following as species which have 

 migrated northward from the Soldado region as a centre of develop- 

 ment: Ostrea cremdimarginata Gabb, 0. pidaskensis Harris, 0. 

 thirso3 Gabb, Modiola cf. alabamensis Aldrich, Venericardia alticostata 

 Con., T\ planicosta Lam., Meretrix cf. nuttaliopsis Heilprin, Lyria 

 wUcoxiana Aldrich var. aldrichiana n. var., Levifusus pagoda 



