ACTINIARIA 



233 



developed siphonoglyphes. 16 to 18 (6 + 6 + 4 (6)) pairs of mesenteries perfect, the last cycle of these latter 

 often consisting of a perfect and an imperfect mesentery. Most mesenteries confined to the proximal part 

 of the body. At least the younger mesenteries developed according to the rule of Actinostola. Parietobasilar 

 and basilar muscles well developed. Perfect mesenteries generally sterile; when the perfect pairs are more 

 than 16, the exceeding pairs are often fertile, the weaker mesenteries of the third cycle also often fertile. 

 At least the stronger imperfect mesenteries fertile. The fertile mesenteries have filaments. 



The genus Stomphia is on one side nearly related to Actinostola, on the other side it recalls Sicyonis 

 in several characters. The j-ounger mesenteries are f. inst. developed as in Actinostola, while in Sicyonis 

 the Actinostola-Tule does not distinctly appear. P'urthermore, several cycles of mesenteries have reproductive 

 organs in Stomphia as well as in Actinostola, wliile in Sicyonis only the last cycle is fertile. The fertile mesen- 

 teries are provided with filaments in Stomphia and Actinostola, but as a rule not in Sicyonis. Stomphia agrees 

 with Sicyonis in the mesenteries being more richly developed in the proximal than in the distal part, and in 

 the double number of mesenteries of the second cycle in four (or six ?) exocoels or, with another interpreta- 

 tion, in the rapid growth of the mesenteries of the third order in certain exocoels (compare p. 216). The 

 mesogloea of the column is generally thinner in Stomphia than in both the other genera, though also in Acti- 

 nostola spetsbergensis, especially in young specimens, the column may be rather thin. On the other hand the 

 body- wall is sometimes thickened in Stomphia (compare below). A peculiarity, often displayed by the Stom- 

 phia-species in contracted state, is this that the central part of the pedal disc is extended tap-like. Sometimes 

 the pedal disc of Actinostola spetsbergensis has the same peculiar appearance. 



To the genus Stomphia the following species certainly belong : the type-species, St. coccinea (O. F. 

 Miill.), St. polaris (Dan.) and St. vinosa (Mc. Murr.) Verr. Concerning the last species, which Mc. Murrich 

 has described as Paractis vinosa, Verrill (1899 p. 295) has put forth that it is a Stomphia, which opinion 

 I fully share. It is true, that Mc. Murrich does not mention more than 32 mesenteries (32 pairs compare 

 Verrill 1. c), but the broad pedal disc indicates that in this part there have been more mesenteries, which 

 Mc. Murrich has not observed. Verrill supposes that also Cymbactis faeculenta Mc. Murr. is a Stomphia. 

 To judge from Mc. Murrich's description, this is certainly not the case. Mc. Murrich namely says that 

 this species is provided with about 96 tentacles but not more than 24 pairs of mesenteries. Evidently there has 

 been one more cycle of mesenteries developed in the distal part, — as in the Actiniaria the number of tentacles 

 is not greater than that of the mesenteries — which Mc. Murrich has not observed. The mesenteries is 

 therefore here probably more numerous in the distal than in the proximal part, while it is just the other way 

 in Stomphia. On the other hand, it is very probable that Cymbactis selaginella, described by Stephenson 

 1918, is a Stomphia, though the body-wall is considerably thickened here. The whole organisation and the 

 exterior of this species as well asStephenson's^ information that "a curious little imperforate mound arises 

 from the concave centre of the basal disc" speak for this opinion. Such a "mound" is, as I have stated above, 

 characteristic of Stomphia. Further the presence of "small single mesenteries" in the proximal part recalls 

 Stomphia. Thus I think that Cymbactis selaginella is a Stomphia-species. 



Verrill (1899 p. 217) declares that large specimens of Stomphia carneola = St. churchiae = 5^ 



1 Compare p. 211. 



The Ingolf-Expedition. V. 9. 30 



