ATLANT. DEEP-SEA EXPED. 1910. VOL. III]. 



SCYPHOMEDUSAE. 



11 



The rhopalia (pi., figs. 7 and 8) are on the exumbrellar 

 side provided with a rather short keel, which is bent 

 abruptly at the transition from the margin to the covering 

 scale. No ocellus could be observed; TV. globifera shares 

 this character with the two other deep-sea species: N. rubra 



Fig. 6. Median diagrammatic section of Nausithoe globi- 

 fera showing the arrangement of the organs (from a 

 camera-drawing), rh. = rhopalium, m. = ring-muscle, 

 g. = gonads, s. = gastric wall, g. c. = gastric cirri. 



and N. atlantica, A small lappet can be traced at the 

 base of the rhopalium, but it is no more developed than 

 in most other species of Nausithoe, and is by no means 

 comparable to those of N. atlantica. 



smooth. The entire stomach is almost of the same length 

 as the bell, or a little longer. The numerous rather stout 

 cirri are simple, arranged in a single row, but so crowded 

 that they appear to be in a double row. 



At a first glance we might think that the position of 

 the gonads (see pi., fig. 6) would exclude this species 

 from the genus Nausithoe. We observe a pronounced 

 arrangement of the eight gonads in pairs, the origin of 

 this arrangement must clearly be looked for in an inter- 

 radial approximation and a perradial separation of the 

 gonads. In this respect we have a typical Nausicaa, but 

 in this species the arrangement is far more specialized 

 than in the preceding one. It is evident that N. atlantica 

 illustrates a transition stage, and as regards the gonads, 

 the series from N. punctata through N. picta and N. at- 

 lantica to N. globifera is so closely related that a gene- 

 ric separation based on this character seems to be out 

 of the question wherever we try to draw the limits. 

 Moreover all the other characters of this species corre- 

 spond so well to those of the other representatives of 

 Nausithoe that I do not hesitate to refer it to this genus. 



Station 



Lat. N. 



Long W. 



Depth in 



Number of 



D 



Measurements in mm 

 = total diameter 









metres 



specimens 



C 



= diameter of central disc. 



10 



43° 26' 



9° 20' 



? 



1 



{ 



D = 17 

 C = 9 



88 



45° 26' 



25° 45' 



1000 



1 



{ 



D = 14 

 C -= 7-5 



90 



46° 58' 



19° 6' 



5C0 



2 



{ 



D = 15-17 

 C = 7-5—8-5 



98 



56° 33' 



9° 30' 



500 



2 



{ 



D = 15-16 

 C = 8-5-8 



101 



57° 41' 



11° 48' 



500 



1 



{ 



D = 15 

 C = 7 



The nettle-spots of the exumbrella are in the marginal 

 parts of N. globifera more densely crowded on the lap- 

 pets and between the pedalia, and round the rhopalia 

 we find a considerable accumulation of nettle-spots. 



On the subumbrellar side the ring-muscle forms an 

 opaque and conspicuous though narrow ring. Inside of 

 this ring (see textfig. 6) we see how the ring furrow of 

 the exumbrellar side causes a very prominent ring on the 

 subumbrella; the large sexual organs are situated on and 

 above the inner side of this ring. The gonads stretch far 

 up into the bell, almost reaching the place of attachment 

 to the stomach. The stomach is of a rounded quadran- 

 gular shape, its walls hanging like folded curtains in the 

 cavity of the bell. The lips are slightly thickened and 



Seven specimens of N. globifera were taken, as shown 

 in the table above: 



The specimen from Stat. 10 bore no specification of 

 depth, but at the other stations, the medusa has only 

 been found in hauls from great depths. This species 

 occurred only in samples from the eastern Atlantic, and 

 seems to correspond to the preceding species both in 

 its bathymetrical and geographical distribution, although 

 it has been taken a little farther north (see the map, fig. 5). 



Atolla Haeckel. 



The description of this interesting genus was given 

 by Haeckel 1 ) in the Challenger Report, founded on an 

 antarctic medusa described as Atolla Wyvillei. In a pre- 



*) Report on the Deep-Sea Medusae, (Zool. Chall. Exp., Vol. 4), London 1881, p. 111. 



