Gr. Y. and A. F. Dixon — On Bunodes thattia, etc. 311 



Nat. Hist. ser. 2, vol. xiv., p. 283), which the same author 

 repeated in Tenby, and supplemented in his Actinologia Britan- 

 nica. 



GENERAL DESCRIPTION. 



Form. 



Base. — Adherent to rocks; exceeding the column ; the lines of 

 the insertions of the mesenteries scarcely visible. 



Column. — Flat or sub-conical in contraction; pillar-shaped or 

 cylindrical in extension, rising to full twice the diameter. The 

 lines of the insertions of the mesenteries are usually scarcely vis- 

 ible, but when the animal is much dilated, they appear as marked 

 depressions. The surface is corrugated, not pierced with cinclides, 

 and studded with an indefinite number of vertical rows of sub- 

 equal and equidistant suctorial warts, which run between every 

 alternate pair of the lines of the insertions of the mesenteries from 

 the base to the margin of the disk, where the topmost wart of the 

 row usually stands, raised conspicuously on the slight parapet. 

 The substance is firmly fleshy. 



Disk. — Flat or slightly concave ; hardly, if at all exceeding the 

 column; bounded by a low parapet, marked by the lines of the 

 insertions of the mesenteries. 



Tentacles. — Indefinite in number, 30-60; submarginal; appa- 

 rently in two or three series; all sub-equal; in length equal to half 

 the diameter of the disk; highly retractile; at times presenting a 

 fluted appearance ; in extension, the inner tentacles are stout at the 

 base, and from about half their length taper to a blunt point, the 

 outer tentacles being less stout, and of equal length; in contraction, 

 a tentacle may be reduced in diameter, so as to resemble a thread, 

 or in length, so as to resemble a wart. When the animal is well 

 expanded, the inner tentacles are nearly erect, the intermediate 

 over-arching outwards, and the outer horizontal or -slightly droop- 

 ing. They readily grasp objects presented. 



