120 THE BERMUDA ISLANDS. 



where the entrance into the interior is situated. Tlie color, 

 according to the inclosed label, was "spinach-green," but this 

 must be taken as applying only to the upper part of the 

 column, the lower part and the stolons being brown or sand- 

 colored. The disc was " apple-green," and the tentacles green. 



The column upon the outside is covered by a cuticle, in 

 which are sparingly imbedded foreign bod.ies. The ectoderm 

 is separated from the cuticle by a layer of mesoglcea, and con- 

 sists of cells arranged in groups separated by partitions of 

 mesoglcea, but not showing the degeneration which occurs in 

 Z. sociatus. The mesoglcea is comparatively thick, and consists 

 of a homogeneous matrix containing (1) numerous anastomos- 

 ing spaces more or less filled with cells, and (2) granular cells 

 which give rise to delicate processes which enter into connec- 

 tion with other granular cells, and with the spaces just men- 

 tioned, and with the ectoderm and the endoderm. Some sug- 

 gestions regarding the origin and function of these structures 

 will be found in connection with the description of M. tuber- 

 culata which follows. The endoderm of the column is low, 

 and consists of more or less spherical cells, usually containing 

 zooxanthellse. A delicate layer of muscle fibres arranged cir- 

 cularly occurs between the endoderm and the mesoglcea. 



At the upper part of the column a well-developed double 

 sphincter muscle occurs, imbedded in the mesoglcea. It is 

 stronger than that found in Z. sociatus, and more nearly 

 resembles that described by Erdmann' and Hertwig' in Z. 

 Danx.{?) 



The tentacles, according to the brief notes taken of the liv- 

 ing specimens, are " short, 50-60 in number, in three rows." My 

 preparations, however, show that the last statement is erro- 

 neous, the tentacles being arranged in two cycles only. Their 

 ectoderm is not imbedded in the niesoglrea, nor is there a 

 cuticle covering it. The ectodermal muscle processes of the 



1 A. Erdmann. Ueber einige tieue Zoantheeu. Jen. Zeil. XIX. 1885. 



2 R. Hcrtwig. Supplement to report on the Acliniaria. Zooloj'y of tlie Voya"e 

 of H. M S. Challenger. Vol. XXVI. 1888. 



