ACTINIANS FROM THE BAHAMA ISLANDS 115 



cavity is drawn up like a purse and the body wall bulges out and forms 

 a tubercle." 



The upper portion of the column, which, in completely contracted 

 individuals, forms the apex, is destitute of tubercles and is furnished 

 with numerous longitudinal ridges. The sphincter muscle is strong 

 and has the form represented in fig. 8, being simple, though showing 

 a tendency to be divided into two parts, an evident constriction {cr) 

 occurring upon it. This is not an individual peculiarity, as I have 

 found it in three individuals examined, and it is interesting as forming 

 an intermediate condition between the simple sphincter of I. tubercula- 

 tus and the double one of the genus Zoanthus. 



The tentacles are arranged in two rows, and their number seems to 

 be double that of the pairs of mesenteries. 



The mesenteries are arranged on the microtype, and vary in num- 

 ber in the different individuals from eighteen to twenty-three pairs. 

 They are much more slender than those of /. tuberculatus, and though 

 thickened towards their insertion with the column wall, yet this thick- 

 ening is slight when compared with that of tuberculatus. Two or three 

 slightly elongated (in section) canals are found in the thickened portion 

 of the perfect mesenteries, the imperfect ones containing but one canal. 

 No reproductive organs occurred in any of the specimens examined. 



The stomatodagum presents a well-developed siphonoglyphe, and 

 its surface is thrown into numerous marked ridges which correspond 

 in a general way, but not accurately, with the intervals between suc- 

 cessive pairs of perfect mesenteries. 



LIST OF REFERENCES 



1886. Ellis, J. — The Natural History of Many Curious and Uncommon Zo- 

 ophytes collected from Various Parts of the Globe, systematically arranged 

 and described by Daniel Solander. London. 1786. 



1817. Lesueur, C. a, — Observations on Several Species of the Genus Actinia; 

 illustrated by figures. — Journ. Acad. Nat. Sci. Philadelphia. Vol. I. 

 1817. 



1828. ■ Gray, J. E. — Spicilegia Zoologica. London. 1828. 



1850. DucHASSAiNG, P. — Animaux radiaires des Antilles. Paris. 1850. 



i860. DucHASSAiNG, P. ET MiCHELOTTi, G. — Memoire sur les Coralliaires des 



Antilles. — Mem. de VAcad. Sci. Turin. Ser. 11. Tome XIX. i860. 

 1864. DUCHASSAING, P. ET MiCHELOTTi, G. — Supplement an Memoire sur les 



Coralliaires des Antilles. Mem. de VAcad. Sci. Turin. Ser. II. Tome 



XXII. 1864. 



