ACTINIA. 5 



are present ; but irregular shallow furrows are formed by contraction in these preserved 

 specimens. In all cases the tentacles are exposed, and they agree generally with the 

 description given by McMurrich, in his account of the species (10, p. 247) from a 

 specimen from Calbuco, both as regards number and arrangement and relative size. 



The oesophagus is generally widely expanded, and in the majority of the 

 specimens is almost indistinguishable from the portion of the oral disc inside the 

 tentacles. But in one of the more contracted specimens the lip of the oesophagus is 

 easily distinguished, but the corrugations are continued radially over the oral disc, 

 running between and a short distance up the bases of the tentacles. The siphonoglyphs 

 are in no case well marked. The foot-disc is well-marked and strongly adherent. 



The more minute anatomy agrees generally with McMurrich's description. The 

 mesogloea of the body-wall is variable in thickness, and in one specimen, just 

 below the sphincter, is nearly 2 mm. thick, from which in an upward direction it thins 

 rapidly to less than 1 mm. The mesogloeal sphincter exhibits no trace of layering, 

 having a simple reticulate structure in transverse section. Transverse sections of the 

 tentacles exhibit the same appearance of portions of the ectodermal epithelium being 

 cut off and apparently enclosed in the mesogloea, as described by McMurrich, due to 

 contraction and the unusual thickness of the mesogloeal layer. 



The mesenteries in number and arrangement agree with McMurrich's descrip- 

 tion, but I cannot confirm the hermaphroditic condition described for the species. 

 In the specimen selected for histological work no spermatozoa were found, and the 

 ova were large and well-developed. Otherwise the ' Discovery ' specimens agree 

 well with McMurrich's description, and I have no hesitation in placing them under 

 this species. 



Family ALICIID^. Duerden (1895). 



AcTiNiARiA with a large, flat, contractile base. Tentacles simple, cylindrical and 

 entacmseous. Column wall with simple or compound hollow tubercles or vesicles, 

 covering the greater part of the column, arranged mostly in vertical rows. Sphincter 

 muscle endodermal and diffuse, variable in amount of development. No cinclides or 

 acontia, margin with or without acroragi. Mesenteries arranged in several cycles of 

 which usually more than one is perfect. 



Genus Cystiactis, M. Edw. 



Aliciidse having the column covered with simple vesicles. Tentacles of variable 

 length, in one, two, or three cycles. Numerous perfect mesenteries ; sphincter muscle 

 moderately well developed. 



Cystiactis Antarctica. 



A single specimen, bearing the label " McMurdo Bay, Winter Quarters, 28.2.02." 



Depth, 20 fathoms. 



z 2 



