Haddon and Shackleton — A Revision of the British Actinice. 657 



Dimensions. — " Column, 3-5 times as high as broad " (Norman). Height of 

 column, when fairly extended (in spirit), 13 mm. ; diameter of withdrawn 

 capitulum, 3— 4 mm. In the "button" condition the height is much less, about 

 4—5 mm., or even less. Some West of Ireland specimens have, in spirits, a height 

 of 15 mm., diameter of capitulum 5—6 mm., diameter of middle of column 3-4 mm. 



Locality. — Shetlands, W. and S.W. Ireland. The exact localities for this species 

 are as follows : — " Living on sponges, Phakellia ventilabrum and P. robusta, 

 Normania crassa, Ocea7iapiajeJre?/sii, &c., in very deep water, 110-170 faths., 20-25 

 miles N.N.W. off Burrafirth Lighthouse" (A.M.N.), (PL lviii., fig. 34); St. Magnus 

 Bay, Shetland, 1867; " Porcupine, 1869, St. 8, 100-159 faths." [off Galway Bay, 

 W. Ireland]. The foregoing are in Canon Norman's collection. 80 faths., 40 miles 

 S.W. of Cape Clear, Co. Cork, 1885 (A.C.H.), (PI. lviii., fig. 36); 80 faths., off the 

 Skelligs, Co. Kerry, July 13, 1886 (A.C.H.), (PI. lviii., fig. 35); 126 faths., off 

 Achill, Co. Mayo, 1890 (A.C.H.). 



This species is subject to considerable variation in general appearance, so 

 much so that we at one time thought that the forms we had under review might 

 belong to two species. This is the "squat button-like form" of Ridley (/.c). 

 There can be no doubt that this is the " Zoanthiis stdcatus? — dispersed in patches 

 on the surface of Desmacidon jeffreysii, from Shetland," of Bowerbank. Hertwig 

 (1888, Suppl. "Chall." Kept. Actiniaria, pp. 446-48) doubtfully refers a colony 

 of "Palythoa" to this species from Inaccessible Island, Tristan d'Acunha (S. 

 Atlantic), 60-90 faths. From Erdmann's anatomical investigations of these 

 specimens it is certain that they belong to the genus Parazoanthus. The species is 

 certainly very close to P. anguicoma ; but we consider that the slight difPerences 

 in the external characters, together with the "considerable hollow expansion" of 

 the encircling simis ("ring-canal") invariably opposite the insertion of the 

 mesenteries, are sufficient to separate the two species, and for the latter we would 

 propose the name of Parazoanthus hertwigi. 



Body-wall (PI. lix., figs. 11, 12). — The ectoderm, where present, is continuous, 

 and is covered by a thin cuticle. It forms a layer of variable thickness, and 

 consists of columnar cells containing deeply staining granules, and of oval 

 nematocysts which do not readily stain. Incrustations, consisting of sand spicules, 

 foraminifera, &c., are fairly numerous, and are embedded both in the ectoderm 

 and in the mesogloea. There is a well-developed encircling sinus, which lies 

 beneath the incrustations. It is of variable thickness, and is frequently crossed 

 by strands of mesogloea ; but these strands are not at all so thick as those in 

 P. axinellce, and the sinus in consequence presents a much less broken appearance 

 than in that species. Branching and anastomosing canals, very similar to those 

 which we describe for Z. coppingeri (1891), connect the encircling sinus with 

 the ectoderm. Nematocysts are frequently to be found in the encircling sinus. 



TBANS. EOT, DUB. SOC, N.S. VOL. IV., PAET XU. 5 A 



