190 Notes on Some Actinians from the Bahama Islands, 



the lower is of some length and in its upper part is composed of a 

 few large cavities which occupy the entire thickness of the meso- 

 gloea, lower down the cavities becoming smaller, but being for the 

 most part more or less circular. The figure will however give a 

 better idea of its arrangement than many lines of description, and 

 from it it will be seen that in the number and arrangement of the 

 muscle cavities the sphincter diflfers from that of any other form 

 which has hitherto been described, particularly from that of the 

 form described by Hertwig ('88), as Z. Danae, the sphincter of 

 which has been described by Erdmann ('85), and which might 

 possibly be considered identical with the form under considera- 

 tion. 



The tentacles are completely infolded in the majority of the in- 

 dividuals of the colonies I have examined, being visible, however, 

 in a few cases. They are short, as is usual in Zoanthids, and are 

 arranged in two cycles, their number being in the neighborhood 

 of fifty, fifty-six in one specimen in which they could be counted. 

 Nothing worthy of note was observed in connection with the disc, 

 but in connection with the stomatodaeum it may be stated that its 

 siphonoglj^ph was deep, about one-third of the total surface of 

 the stomatodaeum being occupied by its smooth walls. 



The mesenteries are arranged in the microtype (bi-achycnemic, 

 Haddon), and there are about 28 to 32 pairs. Each has a single 

 lacunar space near its point of attachment to the column wall, and 

 its mesogloea is thinner than is usual. Three of the individuals 

 were sexually mature and it is interesting to note that both ova 

 and spermatozoa were present in the same individual, this species 

 like that observed by Erdmann ('85) being hermaphrodite. 



Isaurus Duchassaingi (Andres). 



Synonyms: Zoanthus tuber culatus. Duchassaing & Michelotti. 1860. 

 Antinedia tuberculata. Duchassaing & Michelotti. 1864. 

 Antinedia Duchassaingi. Andres. 1883. 



This species was originally described by Duchassaing, in a 

 paper ('50) to which I have not access at present as Zoanthus 

 tuberculatus, the generic name being supplanted in a subsequent 

 paper ('64) by Antinedia. In my paper on the Actiniaria of the 

 Bermudas ('89a) I considered this latter genus to be identical with 

 the genus Mammillifera as defined by Erdmann ('85); since then 

 Haddon, in a paper written in conjunction with Miss Shackleton, 



