ACTINIARIA 



numerous, unto 15. The pennons vary in appearance, but their inner and outer parts look almost alike. The 

 parietal muscles are weaker than in the adult specimens and more elongated. The ciliated streaks are not 

 developed on the directives, but they are present on the 4 other pairs of the first order. 



Genus Siphonactinopsis n. gen. 



Diagnosis: Halcampoididae with the basal end rounded. Column cylindrical, of considerable length, 

 smooth, without "//a/cam^a-papillae", not divisible into regions, without spirocysts and sphincter. Ten- 

 tacles short, conical, 40 in number, not bulbously swollen in the apex, the inner tentacles longer than the 

 outer ones. Only one, a ventral, siphonoglyphe, not elongated below the actinopharynx. Conchula absent. 

 Pairs of mesenteries 20 (10 -f- 10) all perfect and fertile. 2 pairs of directive mesenteries. Parietal muscles 



a little differentiated. 



Siphonactinopsis laevis n. sp. 



PI. 2. Fig. 9. 



Diagnosis: Ectoderm of the column with nematocysts, about 17 20 // long, densely packed just 

 below the tentacles. Ectoderm of the tentacles with numerous spirocysts about 36 38 X 5 // in size and 

 with numerous nematocysts (22 29 X 2//). Longitudinal muscles of the tentacles well developed, with 

 palisade-shaped folds. Nematocysts of the actinopharynx partly typical, 28 x 3 4 fi in size, partly broader 

 in the basal end and with distinct basal part to the spiral thread (length 24, breadth 5 /*) . Pennons of the 

 mesenteries strong, in transverse-sections of considerable length with rather high, branched folds; as these 

 folds are of equal height they make the pennons look like combs. Outer part of the mesenteries issues from 

 the pennon in its most external parts. Parietal muscles not strong, consisting of low, though closely packed, 

 a little branched folds, not expanded upon the column. Marginal stomata large. Well developed ciliated 

 streaks. 



Colour? 



Dimensions: in contracted state, length 5,5 cm, breadth unto 2,5 cm, inner tentacles i cm long, 

 outer tentacles about 0,5 cm. 



Occurrence: Greenland? without distinct locality. (Habitat questionable!) I sp. 



Exterior aspect: The state of preservation was rather good, wherefore I can give a fairly suffi- 

 cient description of the organisation. The greater part of the ectoderm of the column was, however, lost. 



The proximal part of the animal is rounded and involved. The elongated column shows no sign of 

 being divided in regions and is devoid of papillae and other off-shoots. In consequence of the strong con- 

 traction the column is deeply transversely furrowed, while the insertions of the mesenteries on the outside 

 are indistinctly marked. The distal end of the column is in certain places crenelated. Whether these crene- 

 lations are a normal feature or only due to the contraction I cannot decide, as this part of the animal was 

 not well preserved. No distinct fossa is present. The tentacles are 40 in number, probably arranged in three 

 cycles. As some of the tentacles are invaginated, it is, however, difficult with certainty to ascertain this ar- 

 rangement. They are short and conical, the inner tentacles almost twice as long as the outer ones. The oral 

 disc is rather small. There is no distinctly marked entrance to the siphonoglyphe. The actinopharynx is 



15* 



