TRACHYMEDUSAE SS 



Stns 1600 (470-0 m.) and 1602 (175-0 m.), both off the coast of Angola, where an upwelling of 

 cold water from the deep layers takes place. This will be further discussed in the General Section. 



Distribution. Widely distributed in the deep parts of the great oceans. In the eastern part of the 

 North Atlantic it occurs as far north as off the south and west coasts of Iceland, in the western part 

 off the Newfoundland Bank. It has never been found in the Mediterranean, but it seems to be 

 generally distributed in the Atlantic basin as far south as a little beyond the latitude of the Cape of 

 Good Hope. 'Discovery' found it in 35'^ S, and by ' Valdivia' it was taken in one locality in 42' S, 

 14° E, south-west of South Africa. It is also generally distributed in the Indian Ocean north of about 

 35° S. In the Pacific it has only been recorded from Japan and from the tropical eastern region. In 

 contradistinction to most other bathypelagic medusae, this species does not approach the shelf of 

 the Antarctic Continent; it seems to have a fairly distinct southern limit of distribution in about 

 35^ or 40° S. 



Sminthea eurygaster Gegenbaur 1856 



1856 Sminthea eurygaster Gegenbaur, p. 245. PI. 9, figs. 14-15- 



1879 Trachynema eurygaster Haeckel, p. 260. 



1879 Marmanema mammaeforme Haeckel, p. 262. 



1910 Sminthea eurygaster Mayer, p. 383. Text-figs. 226-7. 



Occurrence: St. 256. 23. vi. 27. 35° 14' S, 06° 49' E. West of Cape of Good Hope. Net: TYF 850-1 loo(-o) m. 



2 specimens. 

 St. 282. 12. viii. 27. 01° 11' S, 05° 38' E. Gulf of Guinea. Net: TYF 30o(-o) m. i specimen. 



One of the specimens from St. 256 is in a good condition, 6 mm. wide, with well-preserved gonads 

 close to the ring-canal. The specimen from St. 282 is somewhat shrunk, but in this specimen also 

 the gonads are well preserved. 



Distribution. Mediterranean; Bay of Biscay; near the Azores; Canary Islands; off the north 

 coast of Brazil; in the surroundings of the Amirante and Chagos Islands in the Indian Ocean. Now 

 found in two localities off the west coast of Africa. 



Genus Arctapodema Dall. 

 The first two species of this genus were described by Vanhoffen (19026, pp. 65 and 66) as Homoeonema 

 antphim and macrogaster . Maas (1906^*, p. 5) gave a new description and numerous figures of 

 H. amphim and made it the type of a new genus, Isonema. This name being preoccupied, Dall (1907, 

 p. 661) replaced it by Arctapodema. Mayer (1910, p. 387), however, retained the name Homoeonema 

 (the great confusion concerning this name is discussed in Kramp 1947, pp. 14 ef seq.). 



In igiza Vanhoffen added three new species to the genus: Isonema antarcticum, australe and 

 tetragonium. Ranson (1936, pp. 156 et seq.) accepted the generic name Arctapodema and provisionally 

 retained all of the five species, whereas Thiel (1936, p. 26) united them all, together with Pantachogon 

 scotti Browne, with Homoeonema platygonon {sensu Browne). A new species, Isonema najadis, was 

 described by Pell (1938, p. 926); it is undoubtedly identical with Arctapodema album. 



With the exception of A. album, none of the species have been observed since they were described 

 by Vanhoffen, but three species are represented in the Discovery collection: amplum, antarcticum 

 and australe, and I am able to state that they are distinct species. I am inclined to think that A. tetra- 

 gonium is identical with amplum (see below). Vanhoffen's (19026) description of A. macrogaster was 

 based on one badly preserved specimen (reconstructed in PI. 10, fig. 22); it may possibly be identical 

 with A. australe, but an identification of these two species is still uncertain. 



With a slight alteration of the definition of 'Isonema' as given by Maas, Arctapodema may be 

 characterized as follows: Rhopalonematidae without a gastric peduncle; with urn-shaped stomach; 



.VN . H- 0: 



