.314 BULLETIN OF THE 



Ophiactis humilis, &c). If, therefore, these zones of sea hottora were 

 to-morrow turned to stone, we should find a certain separation of species, 

 but there would be overlapping species that would connect the fossils, 

 as of one formation. Such are the vertical relations. The* horizontal 

 relations can only partially be known, except in the direction of the 

 European coast, because there have been no considerable dredgings on 

 the American side, either to the north or the south, and comparisons 

 must be made only with the littoral forms. It is well known that a few 

 of the Florida Ophiurans {Ophiactis Krebsii, Opltiolepis elegans, &c.) 

 have been found as fur as Charleston, S. O, while in the direction of 

 Brazil many species are found ( Ophiomyxa flaccida, Ophiactis Krebsii, 

 Ophionereis reticulata, Ophiothrix violacea, Opltiolepis ])aucispina, 

 Ophiura cinerea, 0. appressa, Amp>hiura Hiisei, Ophiopsila Riisei). 

 One species, Ilemipholis cordifera, has been collected in Charleston and 

 in Rio, but not yet between those points. 



Naturalists seem to overlook the fact, that, although the edges of 

 the Caribbean fauna spread thus wide, they encounter two other 

 fauna?, north and south. At Charleston, Ophiothrix angulata and 

 Amphiura atra are forms not seen on the Florida coast, while at Rio 

 the Ophiura Januarii, Ophioceramis Januarii, and several species of 

 Amphiura attest a region of new marine life. It is already well known 

 that the littoral Ophiuran fauna? of North and Middle Europe and the 

 Gulf of Mexico are not comparable with each other, even the genera 

 being often different. How is it with the deep-sea forms ? One species 

 is identical, — Ophiomyces frutectosus, — and this, strangely enough, was 

 never seen by human eye until within a few months. Two other spe- 

 cies may be identical, — Astrophyton arborescens and Amphiura tenera 

 (=: elegans?). One species is, in the true sense, representative, — 

 Ophioglypha acervata (comp. 0. albida). The remaining fifty-nine 

 species are, so far as we now know, Caribbean. As to the Panama 

 fauna, the similarity between the opposite sides of the Isthmus has 

 already been shown by Liitken, Verrill, and myself. The correspond- 

 ence of the twelve, twin species shown in the following table is some- 

 thing more than casual : — 



Caribbean Fauna. Panama Fauna. 



Ophiura cinerea Lym. Ophiura teres I.vm. 



Ophiolepis elegans Ltk. Ophiolepis variegata Ltk. 



