46 DISCOVERY REPORTS 



the Specimen from St. 1958 is clean ; it was taken in a ' rectangular dredge bag bent on to a Russell frame 

 with skids to raise it clear of deep mud on the sea floor'. In arctic waters also this medusa is most 

 frequently taken at the bottom, though occasionally it may be found swimming in the upper layers. 



Another antarctic medusa, Pedis antarctica Haeckel, has been referred to this genus ; it was found 

 by the 'Challenger' Expedition south-south-east of Kerguelen Island at a depth of 1260 fathoms. 

 Haeckel (1881, p. 15, Pis. 5 and 6, figs. 1-20) gave detailed descriptions and numerous figures of its 

 morphology ; but as the same applies to his description of ' Pectyllis arctica ' ( = Ptychogastria polaris), 

 and as Browne (1903) found 'serious errors' in the description of this latter species, we can regard 

 his description of the former with some scepticism. If Haeckel's account of P. antarctica is 

 correct, this species is entirely diflterent from P. polaris (including opposita), but, unfortunately, the 

 description can never be verified. I have seen the type specimen in the British Museum (Nat. Hist.), 

 and the bottle only contains some tiny fragments, which give no idea of the original appearance of the 

 medusa. As far as I could see, however, the numerous and closely packed tentacles were not arranged 

 in groups as in P. polaris. The ring of tentacles seems to be homogenous, equally thick and dense 

 everywhere on the fragments still available. I found no indication of ' hoher inserierten einzelnen 

 Saugnapfen'; the tentacles are all broken near their base and, as already remarked by Browne (1903), 

 the marks left on the exumbrella may well resemble sucking discs. I have previously discussed the 

 relationships of the third Haeckelian species, P. asteroides, from the Adriatic Sea and the Straits of 

 Gibraltar (Kramp 1947, p. 5) ; this seems to be a true Ptychogastria, though the tentacles are described 

 by Haeckel as hollow. 



Distribution. In northern waters, P. polaris has a circumpolar distribution in arctic and subarctic 

 areas (see the chart in Kramp 1947). In antarctic seas it has now been found in two widely separated 

 areas: about 90° E and 53-61° W. 



Family Halicreidae 



The Discovery collection comprises four genera and five species of the family Halicreidae, namely : 

 Halicreas minimum Fewkes ; Haliscera conica Vanhoffen ; Haliscera racovitzae Maas ; Botrynema brucei 

 Browne ; Halitrephes maasi Bigelow. Most of these species are represented by numerous specimens, 

 and now that I have been able to examine this extensive material I am more convinced than ever 

 that my earlier conception of the delimitation of these species is correct (Kramp 1947.) 



Systematic confusion has occurred mainly because Vanhoff'en (19026), in his 'Valdivia' Report, 

 established five new species of Halicreas and Haliscera, only one of which, Halicreas papillosum, was 

 properly described. This has subsequently been shown to be identical with Halicreas minimum Fewkes 

 (1882). The other four species, Halicreas glabrum and rotundatum, Haliscera alba and conica, were 

 beautifully figured by the artist of the 'Valdivia' Expedition, but the text gave only some scattered 

 remarks on certain distinguishing features. 



Later authors have been much in doubt as to the identities of these species of Vanhoffen's. The 

 confusion was augmented by Thiel (1936) who united three of them, Halicreas glabrum, rotmidatutn 

 and papillosum, in the single species H. papillosum, and combined Vanhofi'en's two species, Haliscera 

 alba and conica with Maas's (19066) species Haliscera racovitzae. Thiel's distribution chart (1936, 

 p. 36) is therefore unreliable. 



I have been fortunate in having numerous specimens of Halicreidae to examine from the same 

 areas whence VanhoflFen's species were derived, and I have never seen any resembling Halicreas 

 rotundatum and Haliscera alba, both of these species being based on very scanty material. I therefore 

 designate Halicreas rotundatum and Haliscera alba as obsolete species on the ground of inadequate 

 description. Nor can we be sure that the figures in the 'Valdivia' Report are reliable. In the case of 

 the lovely coloured drawing of Halicreas glabrum, at any rate, an entirely wrong impression of the 



