ACTINIA. 



Genus Cribrina. 



Cribrinidse with strong endodermal sphincter ; frequently with pseudoacroragi ; 

 ectodermal musculature of discs and tentacles not imbedded in the mesogloea ; column 

 wall provided with verrucse arranged more or less distinctly in vertical rows ; 

 tentacles simple. 



Cribrina octoradiata. 



Bunodes octoradiatus Carlgren, Hamburg. Magalhaens. Sammeh-eise, Zoanth. (1898), p. 20, Figs. 11 and 12, 

 1898. 



This species was formed by Carlgren (1, p. 20) for a number of specimens taken 

 from the Straits of Magellan and other localities in the South Seas. In one of the 

 ' Discovery ' bottles, labelled " Falkland Islands, Port Harris," were fourteen specimens 

 of very similar-looking Actinians. Upon dissection and microscopical examination, 

 however, I find two distinct species — Bunodes octoradiatus, Carlgren, and Parantheopsis 

 cruentata, Couthouy. Both Carlgren (1, pp. 12 and 21) and McMurrich (10, p. 233) 

 comment on the similarity of appearance of this Cribrinid and this Actiniid, and it is 

 interesting to note in this instance Jihat they were apparently found in association in 

 the same habitat. If this is commonly the case it is not surprising that confusion has 

 occurred in previous descriptions of the Actiniid. Unfortunately I have no record as 

 to the colours of the ' Discovery ' specimens, but McMurrich (10, p. 234) describes the 

 colour of the Actiniid as being very variable ; it is possible that when in association 

 the two species may also approximate in appearance when living, and if this be so it 

 at once suggests mimetic resemblance. 



In size the ' Discovery ' specimens of Cribrina octoradiata agree with Carlgren's 

 specimens (1, p. 20). The sixteen rows of verrucse on the distal portion of the column 

 and the sixteen pseudoacroragi are well seen in all the specimens. Usually gravel 

 and broken shell are attached to the verrucse. The number of the tentacles 

 (8 + 84-16 = 32) appears quite constant. The two siphonoglyphs are well marked 

 and quite regular. The sphincter muscle is strongly circumscribed, and may be 

 described in McMurrich's terms (9, p. 20) as of the pedunculate palmate variety 

 (PI. 3, Fig. 16). The section figured is through the space between the pseudoacroragi, 

 but sections passing through the latter show the sphincter projecting from the inner 

 wall, near its base, so that the cavities of the pseudoacroragi project beyond and 

 above the sphincter. The mesenteries number sixteen pairs (8 + 8 = 16), all 

 complete and fertile, including the directives (PI. 3, fig. 18). The longitudinal 

 muscles of the tentacles are ectodermal and transverse sections (PI. 3, Fig. 17) show 

 strong mesogloeal lamellae. The longitudinal muscles of the mesenteries and the 

 parieto-basilar muscles are exceedingly large and strong, and in the contracted 

 specimens are closely packed into a solid mass, so that the various organs are quite 

 dovetailed together (PL 3, Fig. 18). The mesogloeal lamellae of the muscles are long 

 and branched. The circular muscles of the body-wall too are very strong. The 

 strength of the musculature generally is quite a feature of the species. 



