Verr/'U, Kotes on Radiata. 37 1 



No. 6. — Retnew of the Corah and Polyps of the West Coast of 

 America. By A. E. VEUitiLL, 



Presented, April, 1868. 



Recent explorations of the west tropical coast of America, prin- 

 cipally by Mr. F. H. Bradley for the Museum of Yale College, have 

 contributed so much to the knowledge of the Polypi of t}iat region 

 and have so increased our store of specimens, that a new and much 

 more complete catalogue of the species has become indispensable for 

 a proper understanding of the geographical distribution of the ani- 

 mals of this class. The Smithsonian Institution has contributed the 

 species collected by John Xantus, Esq., at Cape St. Lucas. 



In a paper published two years ago,* the writer enumerated nearly 

 all the species then knoAvn from Panama and called attention to the 

 remarkable contrast between the polyp-fauna? of the Atlantic and 

 Pacific coasts of Central America, and the bearing of these facts upon 

 the supposed former connection between the two oceans, across the 

 Isthmus of Panama. 



The additional forms now presented make these contrasts still 

 greater and more remarkable, and add greater force to the evidence 

 tlien brought forward to show that no deep or extensive water con- 

 nection, sufficient to modify the ocean currents, can have taken place 

 since the existence of the species now living upon each coast. 



The Panamian fauna proves to be remarkably rich in Gorgonacea^ 

 no less than 43 species having already been obtained. The genus 

 Muricea appears to attain here its greatest development, since 15 spe- 

 cies, besides several peculiar varieties, perhaps distinct, are in our col- 

 lection from Panama Bay, and others from Acapulco and Peru, while 

 from the West Indies there are but four well-ascertained species. The 

 occurrence of two peculiar, gigantic species of Ravonia, a genus of 

 corals hitherto known only in tlie Indo-Pacific faunie, is noteworthy, 

 and also the presence of a peculiar new form of DendrophylUa. 



The classification here followed is that proposed by the Avriter three 

 years agof with a few changes that have become necessary by a better 

 knowledge of the anatomy of some groups and the discovery of new 

 forms. 



* Proceedings of the Boston Society of Natural History, vol. x, p. 323, 1865. 

 f Proceedings of the Essex Institute, vol. iv, p. 145, 1865. See also Memoirs of the 

 Boston Society of Natural History, vol. i, 1864. 



