494 Verrill, Notes on MacUata. 



be allied to Asteractis, the figure and description not being accurate 

 enough to determine. The name, Anactis, was given under tlie im- 

 pression that it has no tentacles, and in fact it is not certain whether 

 the lines in the central part of the figure are intended to represent 

 tentacles or lines on the disk. 



Sub-order, ZOANTHACEA Verrill. 

 Proceedings Essex Inst., vol. iv, p. 147, 1865; ditto, vol. v, p. 316, 1868. 



Polyps mostly compound, increasing by budding, permanently at- 

 tached by the base, which is generally small, and by stolon-like or 

 membranous expansions from which the buds arise, in compound spe- 

 cies. Walls but slightly muscular, the summit capable of involution 

 with the tentacles. 



In all the species of this suborder, which have been dissected, pe- 

 culiar flattened organs, having a curved or crescent-shaped form and 

 a transversely striated surface, are found attached to the principal ra- 

 diating lamellfTe, near the base of the stomach. These were first de- 

 scribed and figured by Lesueur, who called them " arcuated organs " 

 and supposed them to have the functions of a liver. Dana described 

 them more fully and supposed that they might be branchial organs. 

 The latter view seems most probable, when we consider the character 

 of the outer integument in these animals, which is always thick and 

 firm and often indurated by adhering grains of sand, thus preventing 

 it from acting as an effectual organ of respiration, as it does in most 

 Actinidce. Nor is this want supplied by large tentacles, or by branch- 

 ing tentaculiform organs seen in many Actmians. Therefore there 

 appears to be a necessity for some special branchial organs, but care- 

 ful exalninations of living or fresh specimens can alone determine 

 positively whether the " arcuated organs " are of this nature. 



This group appears to include three families: Zoanthidce, in which 

 the buds arise from basal stolons or membranes ; Bergidce, in which 

 the stolons arise from the sides above the base ; and Orinidm^ which 

 remain simple and have tubular openings upon the disk, through 

 which thread-like organs (acontia ?) are said to be emitted. Perhaps 

 the simple forms referred to Isaura or Sughea may be admitted as a 

 fourth family when more fully studied, but at present no sufficient 

 characters can be given, since all ZoanthidcB must, at first, be simple. 



The genus Sphenopus, referred to this group by Gray, is a free form 

 and appears to be more closely allied to Edwardsia. 



