262 THE SCYPHOMEDUS.E OF THE SOUTHERN HEMISPHERE, 



Species : Nauj)hanta Challengeri. 



Haeckel, System der Medusen. Seite, 487. 



Umbrella cap-shaped, with horizontal flat vertex and vertical 

 side- wall, 1| times as broad as high. Exumbrella with deep 

 circular furrows and 16 radial grooves. Margin of Umbrella with 

 16 pedalise (8 weak scapular and 8 stronger tentacular.) 16 

 marginal flaps oval nearly twice as high as broad, with deep clasp 

 furrow, about £ as long as the radius of the Umbrella. Tentacles 

 cylindrical, pointed, about as long as the radius of the Umbrella. 

 Gonads 8, oval, thick, bulges twice as long as broad, their proximal 

 halves a little broader than their intervals, their distal halves 

 covered by the circular muscle. 



Size : Breadth of Umbrella, 12 mm. Height of Umbrella 

 8 mm. 



Locality : South Atlantic Ocean, not far from the Island Tristan 

 deAcuhna. Lat. S. 32° 24'. Long., W. of Greenwich, 13° 5'. In 

 8,550 feet (1,425 fathom) depth. 16th of March, 1876. Station, 

 335 of the " Challenger " Expedition. "Wyville Thompson. 



Genus. Atolla. 



Ephyride with 16-32 (rudimentary) mai-ginal bodies, and the 

 same number of tentacles, 32-64 marginal flaps, and 64-128 flap- 

 pouches. 8 separate adradial Gonads, which are grouped in pairs. 

 Rhopalia -pouches rudimentary, transformed into narrow glandular 

 canals. 



Species. Atolla Wyvillei. 



Haeckel, System der Medusen. Seite, 488. 



Umbrella quite flat, orbicular, about 6 times as broad as high. 

 Radius of disk of the Umbrella nearly twice as high as the margin 

 of the Umbrella, divided from it by a very deep radial furrow. 

 Manubrium contracted in the middle, 3-4 times as broad as high. 

 Gonads grouped in pairs (in their circumference there are 8 

 elliptic pouches), their perradial intervals are shorter than the 

 interradial. 19-22 (16-32 1) rudimentary marginal bodies, and as 



