EASTERN COAST OF THE UNITED STATES. 



41 



Oculina implicata Agassiz, MS. 



This species forms dense clumps of strong, crooked, intricately coalesced branches, which 

 are round and obtuse at the ends when free. Cells rather small, deep, very little promi- 

 nent, arranged somewhat near together, in spiral lines ; septa in three cycles, very narrow, 

 the inner edge perpendicular, scarcely exsert. Columella papillose, little developed. Pali 

 scarcely apparent. Surface of the ccenenchyma between the cells finely granulous, im- 

 mediately around the cells marked by faint costal radii. The clumps are six or eight inches 

 in diameter and about the same in height ; the branches about half an inch in diameter ; 

 cells one tenth. 



Cape Hatteras and Beaufort, N. C, thrown upon the beach after storms. (Coll. Mus. 

 Comp. Zool.) 



Among a large number of specimens of this species I have seen none that are perfect, all 

 of them being more or less worn. It is closely allied to the preceding, notwithstanding the 

 great differences in its mode of growth and appearance of the cells, and, when large series of 

 specimens of each can be obtained, may prove to be only a peculiar form of the same 

 species. 



Geographical Distribution. 



The eastern coast of North America has been divided into six regions, each characterized 

 by a peculiar assemblage of animals, some of which are confined exclusively to the region 

 in which they belong, while others may extend beyond those limits in either direction, and 

 occur more or less abundantly in two or more of the subdivisions. These regions have 

 been called provinces by Dana, and fauna, by Liitken and other writers. The limits of most 

 of them are well marked, and have been clearly defined by most naturalists who have re- 

 cently written upon this subject. The Polyps have not, however, been hitherto sufficiently 

 well known to be made useful to any great extent in these investigations. The facts 

 which I am now able to present accord perfectly with those that have been derived by 

 others from the study of the Crustacea, Mollusca, and Acalephs. 



The most northern part of the American coast from Newfoundland to the Arctic Ocean 

 belongs to the great Arctic Realm or Kingdom. This has not yet been examined to an ex- 

 tent sufficient to distinguish many of its subdivisions or faunce, yet it has recently been 

 shown by Mr. A. S. Packard, Jr., 1 that the southern portion should be distinguished from the 

 more northern. The former he has named very appropriately the Syrtensian Fauna. To the 

 southward of the arctic kingdom we have the sub-frigid region, extending as far south as 

 Cape Cod along the coast, and impinging upon some of the outer banks or shoals still farther 

 south. This division has been called the Nova Scotia Province by Dana, 2 which is changed 

 to Acadian Fauna by Liitken. 8 The cold-temperate region, extending from Cape Cod to 

 Cape Hatteras, has been called the Virginian Province by Dana. This and the preceding 

 are together nearly equivalent to the Pennsylvanian Region of Milne-Edwards. The warm- 

 temperate region, from Cape Hatteras to the northern part of Florida, has been generally 

 called the Carolinian Province or Fauna. The tropical region south of this, including the 

 southern part of Florida, Bermuda, and most of the West India Islands, does not come 



1 Canadian Naturalist and Geologist. 3 Oversigt over Gronlands Ecbinodermata, af Chr. Fr. Liit- 



2 Crustacea of the U. S. Expl. Exp., by J.D. Dana, 1853, ken, Kjobenhavn, 1857, p. 91. 

 vol. iii. p. 1564. 



MEMOIRS BOST. SOC. NAT. HIST. Vol. I. 11 



