78 



MEDUSA. I. 



The particular aim of my studies on this species has been to elucidate the relation between 

 the European form Tiaropsis muUicirrata M. Sars and . the American Tiaropsis diadcinata L. Agassiz, 

 the identity of which appears to be beyond doubt. 



Before I enter on a discussion of that question I shall, however, communicate the interesting 

 fact, that ^^Tluuunantias escliscliolfzir Haeckel appears to be identical with Tiaropsis iiinlticirrata. 

 Thaumantias eschschoUzii ^■a.?< described and figured by Haeckel in his System der Medusen and has 

 frequently, in text books and manuals, been mentioned as a typical TJianmaiitias. Haeckel's descrip- 

 tion was based on some specimens from Greenland in the Zoological Museum of Copenhagen. I have 

 seen these specimens and found that the large, black ocelli are so conspicuous, that it seems incom- 

 prehensible, how they have escaped the attention of Haeckel, when he examined the individuals in 

 order to describe them. The specimens are certainly the same, which were examined by Haeckel, 

 and not some others, erroneously identified by another person. This is clearly demonstrated by the 

 label being provided with a number referring to a list of the collection of medusae, then in the museum 



a b c 



Fig. II. Fig. 12. Fig. 13. 



Fig. II. Tiaropsis multicirrata Sars. Mouth-lips of a young specimen, 1.5 mm wide. — Fig. 12. Tiaropsis viitlticirrata Sars. Diagram 

 of a young specimen, 1.8 mm wide. — Fig. 13. Tiaropsis nmlticirrata Sars. Radial canals with gonads, a female, b and c male. 



of Copenhagen, written by Haeckel with his own hand. Another specimen, from Egedesminde, West 

 Greenland, has been referred by Levin sen (1892) to the species of Haeckel, and I myself, seing 

 that the specimens collected by the "Tjalfe" expedition quite agreed with the description and figures 

 of Haeckel, I referred them, unfortunately, to ''Thaumantias csclisclioltzii'' without claser examination 

 (Kramp 1913, p. 267 and 1914, p. 419). 



Morphological remarks: 



The base of the stomach is cross-shaped. In quite young individuals (diameter 1.5—2 mm) the 

 mouth-lips are egg-lancet-shaped, entire, without folds (textfig. 11, from a specimen, 1.5 mm wide, from 

 Trangisvaag at the Facroc Islands). Later they become much folded and are besides, in large speci- 

 mens, rather much lobated. There is a stomachal peduncle, very short and broad, but distinctly mar- 

 ked from the subumbrella. Young specimens (when about 2 mm wide) have no stomachal peduncle, 

 the future presence of which is however indicated by a flattened area in the upper part of the sub- 

 umbrella, whereas the exumbrella is evenly rounded on the top (see the diagrammatic figure, textfig. 

 12, drawn from a specimen, 1.8 mm wide, from Trangisvaag, Faeroe Islands). 



