ACTINIARIA 



153 



textfig. 164 I have reproduced the palmate sphincter of the specimen from the Olga-Expedition St. 41. A 

 similar sphincter is developed in the specimen from Finmark. In the specimens from the station 4 (Ingolf- 

 Exp.), and from Greenland, in one specimen from the station 67 (Michael Sars-Exp.) and in one individuum 

 of Leiotealia spctsbergensis the sphincters are of decidedly palmate type without a distinct main lamella. A 

 pinnate sphincter with a thin main lamella is present in the reproduced specimen from Behring's Sound 

 textfig. 163) and in a specimen from the station 25 (Michael Sars-Exp.). As transition stages between the 



Pig. 1 60 



Fig. 161 



Fig. 162 



Textfigs. 160 164. 

 Cribrina spetsbergensis . 



Transverse sections of tentacles (figs. 160, 

 161), of oral disc (fig. 162) and of sphinc- 

 ters (figs. 163 164). (Fig. 160 spec, from 

 St. 52 Olga-Exp.; figs. 161. 163 spec, from 

 Vega-Exp. ; fig. 162 spec, from St. 67 M. 

 Sars-Exp.; fig. 164 spec, from St. 41 Olga- 

 Expedition). 



Fig. 163 



. 164 



pinnate and palmate type we may consider the sphincters of a specimen from the station 52 (Olga-Exp.) 



9 



and of an individuum from New Foundland. In the former there is a very thick main lamella, but not so long 

 that we may regard the sphincter as palmate, in the latter the main lamella is thin at the base, but much 

 expanded inwards and forming a thick irregular triangle. In the sphincter, reproduced on the textfig. 163, 

 streaks of muscle meshes are seen in some places. Such mesogloeal streaks in the sphincters indicate that 

 parts of the mesenteries have been sectioned. All endodermal sphincters as well as the endodermal muscles 

 in common become mesogloeal at the moment when they break through the mesenteries. 



The ectoderm of the tentacles is high and contains numerous nematocysts and very numerous spiro- 

 cysts. The size of the nematocysts in the tentacles and in the actinopharynx and of the spirocysts in the 

 tentacles is seen from the following table, in which also the number of tentacles and pairs of mesenteries and 

 the distribution of the reproductive organs on the directives are stated. 



The Ingolf-Expedition. V. 9. 



20 



