112 ACTINIANS FROM THE BAHAMA ISLANDS 



small, while the lower is of some length and in its upper part is com- 

 posed of a few large cavities which occupy the entire thickness of the 

 mesoglcea, 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 differs from that of any other form which has 

 hitherto been described, particularly from that of the form described 

 by Hertwig ('88), as Z. Dance, the sphincter of which has been de- 

 scribed by Erdmann ('85), and which might possibly be considered 

 identical with the form under consideration. 



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

 viduals 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 disk, but in connection with 

 the stomatodaeum it may be stated that its siphonoglyph was deep, 

 about one-third of the total surface of the stomatodasum being occu- 

 pied by its smooth walls. 



The mesenteries are arranged in the microtype (brachycnemic, 

 Haddon), and there are about twenty-eight to thirty-two pairs. Each 

 has a single lacunar space near its point of attachment to the column 

 wall, and its mesoglcea 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: Zoanthns tuberculatiis Duch. & Mich. i860. 

 Antinedia tuberculata Duch. & Mich. 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 tuberculatiis , 

 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 Mammilli- 

 fera as defined by Erdmann ('85) ; since then Haddon, in a paper writ- 



