SYSTEMATIC AND BIOLOGICAL ACCOUNT 



Muggiaea bargmannae 1 sp.n. 



Many years ago I recorded in my manuscript notes on the distribution of Siphonophores along 

 ' Discovery IPs ' 30 meridian line of stations the occurrence of a new species of Muggiaea at Station 

 663, in a haul from 500 to 250 m. Recently, whilst identifying Siphonophores from part of 

 ' Discovery LPs' o° line of stations, I found this species again. I therefore re-examined much of the 

 ' Discovery ' material of Dimophyes arctica, which the new Muggiaea superficially resembles, and found 

 in hauls from the Antarctic more specimens which had been confused with those of Dimophyes arctica. 

 Unless material is well preserved or stained, confusion of this sort is quite easy, since the new species 

 lacks the ridges found in Muggiaea atlantica and M. kochii (the apex of the nectosac is closer to the 



Sorn 



Cradd 



Vel 



Som 



Text-fig. 63. Muggiaea bargmannae sp.n. A, B, holotype specimen, 'Discovery II' St. 2012, 100-50 m. ; C, baso-ventral 

 parts of four paratype specimens from same station; D, E, apical and basal views of holotype. All figures x 12. 



apical end of the nectophore than in those species). But the mouth-plate is divided, unlike its counter- 

 part in Dimophyes, and the ventral slit in the hydroecial wall is in the mid-ventral line and is shorter 

 than in Dimophyes, so that in lateral view the ventral wall of the hydroecium extends further towards 

 the base, as in the other two species of Muggiaea. This point will be readily appreciated if comparison 

 be made between the ventral view of M. bargmannae given in my Text-fig. 63 B and that of Dimophyes 

 arctica given by Chun (1 897 ft) in his fig. 4 of Taf. 1. 



With the knowledge of this new species I am inclined to think that Dimophyes whose affinities have 

 always been obscure, is most closely related to Muggiaea, especially since its posterior nectophore is 

 obsolescent. In M. atlantica and M. kochii the posterior nectophore has ceased to develop; and no 

 posterior nectophore has so far been found associated with the new species, whose eudoxid has not 



yet been certainly identified. 



1 This species is named after Dr Helene Bargmann. 

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