Part II. — Stichodactylince and Zoanthece. 167 



Homostichanthus anemone (Ellis). 

 (PI. X., fig. 8; PI. XII., figs. 4-6; PL xiv., fig. 2; PI. xv., fig. 1.) 



Actinia anemone, . . Ellis, 1767, p. 436, pi. 19, figs. 4, 5 ; Ellis and Solander, 



1786, p. 6, &c. 

 Hydra anemone, . . Gmelin, 1788, p. 3869. 

 Discoso7na anemone, . Duchassaing, 1850, p. 9 ; Milne Edwards, 1857, p. 257 ; 



Ducliassaing and Michelotti, 1860, p. 38, pi. vi., 



figs. 2, 3 ; Duchassaing and Michelotti, 1866, p. 122. 



Andres, 1883, p. 493. [non M'Murrich, 1889.] 



The base is flat and usually buried in sand for some distance below the surface 

 of the sea-floor; or may be fixed to rocks, gravel, or other foreign bodies. It is 

 thin-walled and semi-transparent, the radiating mesenterial attachments showing 

 through. In diameter it is slightly larger than the lower part of the column, but 

 much less than the upper overhanging region. Particles of sand and gravel may 

 adhere, and occasionally renniants of a coarse cuticular membrane. When not 

 attached, as in the laboratory, the base is very distensable, and preserved examples 

 exhibit radiating and concentric basal foldings. 



The column for its whole length is buried in sand, and is greatly elongated, 

 somewhat cylindrical, erect, smooth, distensable, and devoid of verrucfe. Distally 

 the internal attachment of the different orders of mesenteries is apparent through 

 the thin wall ; an additional cycle of pairs is in this way seen to commence about 

 half-way ujd tlie column, and to extend as far as the apex. Tlie distal region is 

 strongly folded, and, along with the disc, overhangs the proximal region ; in situ 

 this area rests upon the sea-floor, or the whole pol}'!) may be buried so that only 

 the crests of the discal folds are visible. Around the apex of the column are small, 

 obtuse elevations which may perhaps be regarded as acrorhagi. They are a little 

 lighter in colour and correspond with alternate mesenterial spaces. A shallow 

 fossa occurs between the circle of acrorhagi and the outermost cycle of tentacles. 

 In preserved specimens the column is divided into deep longitudinal and trans- 

 verse foldings. When alive the polyps are capable of considerable retraction, 

 and, if disturbed, withdraw themselves for some distance below the surface of the 

 sea-floor. 



The disc is large, and peripherally is thrown into deep folds, nine to twelve, or 

 even more, in number. The central naked area is comparatively small and flat, 

 and the peristome but slightly raised. Generally the disc is only partly retracted 

 so that its diameter is not larger than that of the column ; it can, however, be 

 completely withdrawn so as to be wholly hidden. 



The tentacles are short, smooth, slightly capitate, and arranged in numerous 



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