382 Miss O. M. Rees on Actinostola callosa. 



XLV. — Nates on Actinostola callosa (Verrill) — Dysactis 

 crassicornis {Hertwig). By Olwen M. Kees, B.Sc, 

 U.C.W. Aberystwyth. 



This Actinian was described by Hertwig in [2] as 

 Dysactis crassicornis of the genus Dysactis (Milne-Edwards). 

 It is also described by McMurricli as Actinostola callosa 

 (Verrill). McMurricli obtained his specimen from off the 

 coast of Ecuador, South America. Hertwig- obtained liis 

 from the southern shores of America, 53° 38' S., 70° 56' W. 



A specimen was collected by Mr. II. Vallentin, of Falmouth, 

 during his visit to the Falkland Islands, and recently sent by 

 him to Mr. C. L. Walton, who very kindly passed it on to me 

 for examination. It was picked up on the 5th Sept., 1910, 

 adhering to a root of Lessonia, during an onshore gale (S.W.) 

 in King George's Bay, W. Falkland Islands. 



External Characters of Actinostola callosa. 



This specimen was in a state of contraction, yet all the 

 tentacles were in full view, probably because the sphincter 

 muscle was still expanded. The column is pillar-like, low, 

 and bioad, with the diameter exceeding the height. Height 

 11 mm., diameter of tentacular crown 16 mm., diameter of 

 pedal disc 20 mm. The column-wall is firm and leathery 

 and variously corrugated, owing to contraction. The margin 

 is tentacular. The base is adherent, undulate in outline, and 

 exceeding the column. The oral disk is concave, having the 

 mouth raised on a cone. The diameter of the mouth is 

 7 mm. The oral fissure is bounded by swelling papillae, of 

 which two at either end enclose the entrance to the oesopha- 

 geal grooves. 



The tentacles are very numerous, and cover the whole of 

 the disk. The tentacles lying towards the outside become 

 shorter and also more slender than those near the mouth. 

 The outermost tentacles are so small that they merely project 

 as small knobs above the surface of the oral disk. 



Length of tentacle of outer cycle is 1 mm. ; length of 

 tentacle from the innermost cycle is 3 mm. 



They are arranged in five cycles : 12 + 12 + 24 + 48 + 96... 

 There is a distinct orifice at the tip of each tentacle. The 

 tentacles have •no markings, but the outer ones are paler in 

 colour than the inner. 



The colour of the body-wall is brick-red, the tentacles 

 being of a paler hue with a deep dark band around the 

 summit of the column. 



