120 THE BERMUDA ISLANDS. 



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

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

 must be taken as applying ouly 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 bodies.' The ectoderm 

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

 sists of cells arranged in groups separated by partitions of 

 mesogloea, but not showing the degeneration which occurs in 

 Z. sociatus. The mesogloea 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 

 zooxanthellce. A delicate layer of muscle fibres arranged cir- 

 cularly occurs between the endoderm and the mesogloea. 



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

 sphincter muscle occurs, imbedded in the mesogloea. It is 

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

 resembles that described by Erdmaim 1 and- Hertwig 2 in Z. 



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 niesogioaa, nor is there a 

 cuticle covering it. The ectodermal muscle processes of the 



1 A. Erdmann. Ueber einigc neue Zoantheeu. Jen. Zeit. XIX. 1885. 



2 R. Hertwig. Supplement to report on the Acliniaria. Zoology of the Voyage, 

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



