350 Verrill, Notes on JRadiata. 



occurence in the miocene strata of San Domingo* of several species 

 of shells having the closest affinity to those of the Panaraian Fauna, 

 and in some cases belonging to genera not now living in the Car- 

 ibbean Fauna.f The majority of the associated species are peculiar, 

 so far as known, to the formation, while nearly all of those identified 

 with recent forms (14 species) still inhabit the West Indies. In the 

 same formation 10 species of corals occur, none of which appear to be 

 living, but most of them belong to European and Atlantic, rather than 

 Pacific groups, except a species of Pocillipora, a genus not now living 

 in the Atlantic, but common at Panama and throughout the tropical 

 Pacific. In the paper referred to, it is stated that the Isthmus of 

 of Darien is less than 1000 feet high,J while the tertiary beds of San 

 Domingo have been elevated nearly twice that amount. 



A similar formation, and probably of the same age, occurs near 

 Aspinwall in a railway cut, 1 5 feet above the sea-level,§ from which 

 nine species are recorded as identical with those of San Domingo, 

 and others are probably so. In the museum of Yale College there is 

 a small collection from near Aspinwall, probably from the same lo- 

 cality, in which are specimens of a Clypeastroid, apparently identical 

 with Stoloniclypeus prostratus of the West Indies, but certainly not 

 with *S'. rotundus of Panama. So far, therefore, as the direct geologi- 

 cal evidence beai-s upon this question it would indicate a passage of 

 Pacific forms into the Atlantic during the Tertiary period, rather than 

 the contrary. Yet ^Ir. Carpenter says,]] "As the level of the Atlantic 

 is higher than the Pacific, any such communication must have j^oured 

 the treasures of the Atlantic into the Pacific, and scarcely allowed an 



* On some Tertiary beds in the Island of San Domingo ; from Notes by J. S. Heni- 

 ker, Esq., with remarks on the fossils by J. C. Moore. Quarterly Journal Geol. Soc. of 

 London, vi, p. 39, 1849. On some Tertiary Deposits in San Domingo bj^T. S. Heneken, 

 with notes on the fossil shells, by J. C. Moore, and on the fossill Corals by "W. Lonsdale, 

 op. cit., ix, p. 115, 1853. 



( Mr. Duncan has since described the fossil corals in the same work, — Reprint.) 



•j- The shells quoted as having close analogy with Panamian species are as follows : 



" Cassis, scarcely distinguishable from G. abbreviata, Acapulco. Malea, closely re- 

 sembling M. ringens, Coast of Peru (Panama, Yale Mus.), if it be not identical. Colum- 

 bella, very like 0. pavona, G-ulf of California. The genus Fhos of which several species 

 are known in the Bay of Panama and none in the West Indies, is here represented by 

 four species, all closely related to shells of the Pacific. Venus, nearest to V. gnidia, 

 CaUfornia (Mazatlan, etc.). Area, a large species very like A. grandis. Bay of Panama: 

 no large Area is now found in the Atlantic." 



\ The lowest pass on the Isthmus of Panama is said to be but 287 feet, — Reprint. 



§ Journal G-eol. Soc. Lond., ix, p. 132. 



I Report of the British Association, 1856, page 363. 



