34 VERRILL ON THE POLYPS OF THE 



Family Zoanthid^e. 



Zoanthes Blainville, Diet. Hist. Nat. (1830). Zoanthina Ehrenberg, Corall. des roth. 

 Meer. (1834). Zoanihidce Dana, Zoophytes (1846). Zoanihince Milne-Edwards, Coralliaires 

 (1857). 



Polyps aggregated, permanently fixed upon rocks, shells, etc. The new polyps arise 

 by budding from basal expansions of the walls in the form either of stolons or broad 

 sheets. Column cylindrical, the summit capable of involution. Tentacles short, conical, 

 placed close to the margin of the disk. 



Genus Zoanthus Cuvier. 



Actinia [pars) Ellis (1767); Ellis and Sol. (1786). Hydra (pars) Gmelin, Linn., Syst. 

 Nat., ed. xiii. Zoanthus Cuvier, Tab. Elem. (1797) ; Regne Anim. (1817). Zoantha Lamarck, 

 Systeme des Anim. sans Vert., p. 363 (1801) ; Hist. Anim. sans Vert. (1815) ; Lamouroux; 

 Dana. Zoanthus Ehrenberg, Milne-Edwards. 



Base incrusting rocks, shells, or other foreign bodies, sometimes in the form of thin 

 spreading sheets or bands, at other times as narrow creeping stolons. Polyps arising from 

 the spreading base, elongated, subcylindrical, or pillar-like. The surface of the walls is 

 either smooth and covered with mucus, or protected by a layer of sand closely aggluti- 

 nated to the surface. Disk generally concave, capable of involution, but the polyps con- 

 tract very little in length. 



Zoanthus parasiticus Stimpson, MS. 



This species, which is parasitic on shells, has an incrusting base, smooth and uniform on 

 the lower side of the shell, but giving rise to from fifteen to twenty polyps on the upper 

 side, which diverge in all directions. Polyps variable in height and size, those of the 

 upper central portion generally half an inch in height and one eighth in diameter, while 

 those around the margin of the base are not more than half so large, and much crowded. 

 Base spreading over and completely investing dead shells of Natica, Buccinum, etc., both 

 externally and internally. The substance of the shell in every case has been entirely 

 removed, but the form in all parts is perfectly preserved by the membranes of the polyps, 

 while the cavity is inhabited by a species of hermit crab (Eupagurus j^uhescens). Column 

 pillar-like, smallest in the middle, increasing gradually below, but enlarging rapidly at the 

 summit. Walls thin, covered by a layer of closely adhering, fine sand. When contracted, 

 the summit is slightly concave, and in the medium-sized polyps has seventeen, in the 

 largest twenty-four sulcations, radiating from the centre, which is seldom completely 

 closed. Tentacles forty-eight or more, short, conical. 



Off the coast of New Jersey, lat. 40° N, long. 73° W., in 32 fathoms (Capt. Gedney, 

 Coll. Smith. Ins.). 



This is the only species of the family yet found on our coast north of Florida. In habits 

 it resembles Z. Couchii of England, and, like the latter, will probably be found to assume 

 various forms according to the object upon which it grows. It is a larger species, and the 



