SYSTEMATIC AND BIOLOGICAL ACCOUNT 123 



taken in a haul from 121 m. to the surface in temperatures of from 0-84° to 0-30° C. and salinities of 

 from 3 3-99 % to 33-17 % . 



The recognition of this new species of Muggiaea brings up the total of Siphonophores found in the 

 Antarctic to fifteen. They are: Pyrostephos vanhoeffeni, Marrus antarcticus gen. et sp.n., Stephanomia 

 convoluta, Diphyes antarctica, Muggiaea bargmannae sp.n., Dimophyes arctica, Lensia havock, L. achilles, 

 Rosacea plicata, Vogtia serrata, Thalassophyes crystallina, Crystallophyes amygdalina, Heteropyramis 

 maculata, Chuniphyes multidentata, and Ch. moseri sp.n. The first five and Vogtia serrata are confined 

 to the Antarctic. 



The figured holotype from 'Discovery II' Station 2012 bears the Brit. Mus. (Nat. Hist.) Registei 

 No. 1952. 3. 18. 1. 



Muggiaea delsmani sp.n. (Text-fig. 55 B.) 



In December 1937 I received for identification from Dr H. C. Delsman of Hilversum a small 

 collection of Siphonophores from the Java Sea. From a station at 5 57' S., 108 23' E. came specimens 

 of Diphyes chamissonis, Lensia subtiloides and a new species of Muggiaea which I have named after 

 Dr Delsman and describe below. An interesting point about the record is that the salinity was low 

 for Siphonophores. DrDelsman's note read 'salinity surface 327%,,, bottom (45 m.) 3i-6% . . .a few 

 other stations where the salinity was slightly higher viz. about 33-3 % . All these salinities, however, 

 have been determined with an areometer which possibly gave slightly too low values. At any rate the 

 salinity in the Java Sea hardly ever surpasses the 34 % and at an average is not higher than 33 % '. 



M. delsmani can be distinguished at once from M. kochii, which also has a short somatocyst, by its 

 shallower hydroecium, whose upper wall is more nearly horizontal than in M. kochii. As in other 

 species of Muggiaea the base of the somatocyst lies close to the ventral wall of the nectosac. The usual 

 five ridges are present, and the tip of the nectosac, as in M. atlantica and M. kochii does not come as 

 close to the apex of the nectophore as it does in the new species M. bargmannae. The distal edges of the 

 two mouth-plates are rounded, and there is no sign of a notch in one of them as there is in Lensia 

 subtiloides. 



Reference to Text-fig. 55 B makes further description of the nectophore unnecessary. The eudoxid 

 has not been recognized as yet. 



The figured holotype bears the Brit. Mus. (Nat. Hist.) Register No. 1937. 12. 9. 1. 



Dimophyes arctica (Chun), 1897. 



The only previous records from the Indian Ocean are: (1) One complete polygastric specimen 

 (not one eudoxid as stated by Browne, 1926) recorded by Moser (1925, p. 390). (2) One anterior 

 nectophore from a locality 8° 16' S., 5 1° 26' E., between Providence and Alphonse ; open net, 900-0 fm., 

 recorded by Browne (1926). 



The species was taken in seventeen of the forty-eight ' Discovery II ' hauls that I have examined 

 from the west Indian Ocean ; it was probably breeding at eleven of them. Because of the possible 

 value of this species as an 'indicator' of water masses the details of the catches are given on p. 124. 



The species was not found further north than 06 05' N. lat. It was breeding in a depth not greater 

 than 250 m. as far north as 07° 42-1' S. lat. at a temperature somewhere between 117 and 17-21° C. 



I have accumulated data on the temperature and salinity tolerances of D. arctica from 117 hauls of 

 closing-nets made at sixty ' Discovery ' stations (outside the Indian Ocean) as set out on pp. 1 25 and 1 26. 



Using the higher temperature of the lowest range of any closing haul as the minimum and the 

 lower temperature of the highest range as the maximum, I find that the known range of temperature 



is from —1-13° to 13-26° C. 



16-2 



