372 Annals of the Carnegie Museum. 



discoverer. A smaller form represented by several badly crushed 

 and distorted individuals resembles more or less closely some of the 

 remains which Dr. D. S. Jordan has recently described from the 

 bituminous (Tertiary?) shales at Riacho Doce, State of Alagoas, 

 Brazil, under the generic title of Ellipes. The latter is doubtfully 

 distinct from Diplomystus, but may perhaps be retained provisionally 

 as a subgenus of the latter. A single specimen in the collection is 

 doubtfully identifiable as belonging to Enchodus. 



Regarding the Brazilian fish-remains described by Dr. Jordan, their 

 discoverer, Professor J. C. Branner, offers the following comments in 

 his paper on the Geology of Alagoas, which accompanies that of Dr. 

 Jordan in volume VII of the Annals of this Museum. 



" Dr. Jordan feels some doubt in regard to the exact age of the 

 beds, and he ventures only to say that ' the shales of the Riacho Doce 

 were deposited in an estuary and that their age is Cretaceous or 

 Lower Eocene, possibly Upper Cretaceous.' 



" These fishes form the most important collection of fossils thus 

 far made in the state of Alagoas, and they also make an interesting 

 and valuable contribution to our knowledge of the coast sediments 

 of eastern Brazil " (loc. cit., p. 1 8). 



Now it is an interesting and significant fact that species of the same 

 genus, or at least of very closely related genera, should occur respec- 

 tively in fresh-water deposits of the eastern coast of South America 

 and western coast of Africa, the presumption being that the strata 

 are approximately contemporaneous, — that is to say, early Tertiary. 

 This coincidence points to a similarity of the fresh-water fish-faunas 

 of the two continents extending as far back as the dawn of Tertiary 

 time, and also suggests a correspondence of geological history between 

 the land-masses on either side of the Atlantic. 



An hypothesis which has recently found strong adherents among 

 ichthyologists is that put forward by von Ihering and others, which 

 postulates a late Cretaceous or early Tertiary land-bridge between 

 tropical Africa and South America, possibly in contact with Guiana 

 in the latter continent. This conjectural land-mass, " Helenis," may 

 be supposed to have been populated by the ancestors of modern 

 fresh-water fishes of tropical America, among others by the Lepidosi- 

 renidae, Characinidse, Cichlidae, and Silurida?. A submergence of the 

 area called Helenis took place during Tertiary times, which brought 

 about important changes in the ichthyic fauna, such for instance as 



