ACTINIARIA 



2 distinct siphonoglyphes. Mesenteries numerous, thin, but only 6 pairs perfect. Muscles of the mesen- 

 teries weak. Distribution of the reproductive organs? 



The below described species is probably nearly related to "Actinernus" saginatus and aurelia, but is 

 distinguished from them by the tentacles being devoid of basal thickenings. Unfortunately, on account of 

 the bad preservation of the specimen, I can neither decide, whether the tentacles are arranged in two or three 

 cycles (compare below), nor how the reproductive organs are placed in the mesenteries. So far, it is the most 

 practical to propose a new genus. If it were to be found out afterwards, that "Actinernus" 1 sometimes can 

 be devoid of tentacle-tubercles, /. dubia probably belongs to this genus. 



. dubia n. sp. 



Diagnosis: Pedal disc with a cuticle. Sphincter comparatively weak, filling up only part of the 

 mesogloea, not longitudinally stratified, consisting of small meshes, showing a tendency to transversal strati- 

 fication, distinctly separated from the endodermal column muscles, and not continued in those latter. Ten- 

 tacles smooth to indistinctly longitudinally sulcated, numerous (about 124). Longitudinal muscles of the 

 tentacles and radial muscles of the oral disc ordinarily developed. Oral disc with radial ridges and furrows, 

 especially well developed in the outer part. Actinopharynx of ordinary length. Siphonoglyphes with aboral 

 prolongations. Pairs of mesenteries hexamerously arranged in five cycles (6 + 6 + 12 + 24 + about 24, 

 of which the last as a rule are developed only in the outer exocoels). Only 6 pairs of mesenteries perfect. 

 Longitudinal muscles form weak pennons only in the inner part of the mesenteries. Nematocysts in the 

 tentacles and the actinopharynx numerous, in the former 26 34 X 4 5 p, in the latter 24 41 X 3,5 5 (i. 

 Spirocysts of the tentacles very numerous 19 X 1,5 2 to 67 x 7 ft. 



Colour? 



Dimensions: Length and breadth about 3 cm. Inner tentacles about 1,5 cm long. 



Occurrence: 6o37' N. 2752' W. 799 fms. Temp, at the bottom 4,5 (Ingolf-Exp. St. 78) i sp. 



Exterioraspect: The pedal disc is wide and deeply excavated , on account of its covering a sponge, of 

 which rests remain behind. On several parts of the disc there are fragments of a cuticle. The column is about as 

 long as broad, smooth and of about the same thickness as in Sicyonis. There is no distinct margin. The tentacles 

 are broad at the base, diminishing towards the apex and rather short and thin. They are indistinctly transvers- 

 ally wrinkled ; some of them are longitudinally sulcated. They are devoid of basal thickenings and basal stinging 

 batteries. The inner tentacles are longer than the outer ones of which one part was very small. They were 

 about 124 in number, a little fewer than those of the mesenteries. Their arrangement is difficult to deternu'ne, 

 as the outer part of the oral disc was contracted and not well preserved, and small tentacles in development 

 disturb their agroupment. Besides, they are closely packed on the outer rim of the oral disc. The tentacle 

 cycles are possibly not more than 2 in number, at any rate not more than three. The oral disc is very wide 

 and its greatest part without tentacles, in the innermost part smooth, in the outer with deep radial furrows. 

 There are no gonidial tubercles. The actinopharynx is of ordinary length and irregularly wrinkled. The 

 siphonoglyphes are distinct and provided with aboral prolongations. 



1 Aclinoscyphia (p. 184). 



