194 



ACtlNIAklA 



lidium but larger than those of Anthosactis ingolfi. The thread of the nematocysts is very twisted but is often 

 scarcely visible in the maceration preparations ; for the greater part it is only the very close points 

 of recurvation of the thread which are seen through the wall of the capsule. The inner tentacles 

 are devoid of such a stinging battery. The longitudinal muscles are, on the abaxial side at the base, 

 weaker than on the adaxial, though also on the former side rather strong; further upwards the muscles 

 of both sides are of about equal strength. On the abaxial side the muscles are mostly ectodermal, though 

 also here and there muscles, enclosed in the mesogloea, appear (textfig. 185) ; towards the adaxial side the 

 mesogloeal muscle-meshes are more numerous, so that the muscles may be called meso-ectodermal here 

 (textfig. 186). The radial muscles of the oral disc recall those on the adaxial side of the tentacles and are 

 meso-ectodermal and more strongly developed in the outer parts than in the inner, where they are rather 

 weak. The ectoderm of the actinopharynx is somewhat low, especially in comparison to the mesogloea, and 

 contains few nematocysts of typical appearance, about 22 X 3,5 [i long; on the other hand, the nematocysts 

 with discernible basal part to the spiral thread are rather numerous. They are broader in the basal end and 

 26 34 X about 5 p in size. 



The mesenteries are octomerously arranged, which I have ascertained by the examination of several 

 specimens and also of the type-specimen. Danielssen, however, declares that the mesenteries are hexam- 

 erously arranged, but that is not the case and does not correspond with the arrangement of the tentacles, 

 the agroupment of which Daniels sen has correctly stated. In the specimens with 64 tentacles the pairs of 

 mesenteries were 32 (8 + 8 + 16), in those with 80 tentacles there were in one half, counted from the one 

 directive pair, 20 pairs (4 + 4 + 8 + 4) developed. The four pairs of the last cycle are arranged in an octant 

 next to the one directive pair. The arrangement of the tentacles on the other half indicates that also this 

 part has the mesenteries grouped in the same manner. The eight first pairs of mesenteries are perfect. The 

 longitudinal muscles of the mesenteries are not very strong and form no distinct pennons. The folds are 

 however, numerous but low, with the exception of the innermost part, where they show a little tendency 

 to form weak pennons; in the other parts of the stronger mesenteries they are uniformly developed. The 

 parietobasilar muscles are distinctly marked, but the muscle lamella is not folded, it is extended over two 

 thirds of the length of the column. The transversal muscles are rather well-developed in the distal part. 

 The basilar muscles are well-developed and folded. A small oral stoma is present on the perfect mesenteries, 

 on the other hand, there are no marginal stomata; I have, however, found a rather large aperture about 

 in the middle of one mesentery. The ciliated tract of the filaments is strong, its mesogloea thick and containing 

 numerous cells. The species is dioecious; all mesenteries, at least in the specimens with 32 mesenteries, are 

 fertile. The statement of Danielssen, that the 6(!) first pairs of mesenteries are sterile, is wrong. The 

 acontia are absent. 



Anthosactis ingolfi n. sp. 



Diagnosis: Pedal disc without a cuticle. Column in contracted state with longitudinal furrows 

 in the upper part. Tentacles conical, not longitudinally sulcated, in numbers 48 (6 + 6 + 12 + 24), of 

 which the first and the second cycle are very close. Inner tentacles thicker and longer than outer ones. 

 Longitudinal muscles of the tentacles ectodermal, on the inner side at the base very strong. Oral disc with 



