134 THE VOYAGE OF H.M.S. CHALLENGER. 



a regular eight-rayed shaggy rosette. Arms moderately long and thin, band-shaped, 

 triangular, nearly as long as the diameter of the umbrella, with a tassel-shaped, three- 

 winged bunch of tufts, enclosing a projecting triangular, terminal knob without frills. 

 Horizontal diameter, 80-90 mm. ; vertical diameter, 30-70 mm. 



Habitat. — South-east part of the Pacific Ocean, not far from the island of Juan 

 Fernandez. Station 229 ; lat. 33° 31' S., long. 74° 43' W. Depth, 2160 fathoms. 14th 

 December 1875. (Taken at the same time as Tesserantha connectens, p. 50.) The 

 specimen was pretty well preserved, but the arms were in great measure torn away. 



The umbrella (figs. 1-4) forms a depressed disk, whose central part ("discus") is almost 

 flat, whilst the coronal part ("corona") is sloped gently away. In radial section (fig. 2) we 

 see that, as in all Monodemnias (Versuridce and Crambessida), the body consists of two 

 separate principal parts only connected by the four perradial oral pillars, viz., the true 

 umbrella disk (with gastral cavity and umbrella corona) and the underlying arm disk 

 (with its pendant oral arms). The two principal parts are separated by the spacious 

 central subgenital vestibule (ir) which opens freely to the exterior by four broad interradial 

 subgenital apertures (figs. 1, 7, ig). The gelatinous substance of the umbrella resembles 

 a soft cartilage in consistency, and is of tolerably equal thickness throughout (nearly 

 10 mm.), whilst it suddenly becomes thinned away towards the margin, and is only 

 slightly developed on the lobes. The gelatinous substance of the arm disk is nearly as 

 thick as that of the umbrella disk. 



The exumbrella (figs. 1, 3) is distinguished by a delicate and tolerably regular 

 tabulation, caused by the divisions by the net-shaped connected furrows, of the whole 

 outer upper surfaces of the umbrella into polygonal areas, projecting somewhat convexly, 

 corresponding to the " pedalia" of Nauphanta, Atolla, and other Discomedusas. The size 

 of these exumbral arese increases from the centre towards the periphery ; the diameter of 

 the inner areas amounts to from 4-5 mm., that of the outer areas from 6-8 mm. ; the 

 former are roundish, the latter extended polygonally, quadrangular, hexagonal, or 

 octagonal. An octagonal central area (in the middle of the apex of the umbrella) is 

 first surrounded by a corona of eight adradial areas ; next to these come a second corona 

 of sixteen subradial areas ; the largest and most distinct areas are thirty -two hexagonal, 

 forming a circle, whose distal peripheric corresponds to the coronal canal on the 

 subumbrella (fig. 3). The exumbral areas become less distinct towards the lobe corona, 

 the radial furrows between them pass into the incisions between the marginal lobes. 



Eight sense clubs (four perradial and four interradial) are placed on the umbrella 

 margin (figs. 3, 4), as in all Crambessidas, and particularly in most Rhizostomas. Each 

 rhopalium is here enclosed by the two small pointed lanceolate, ocular lobes (or rhopalar 

 lobes) which diverge outwards. The octants of the umbrella margin, which compose the 

 lobed velarium, project in the form of shallow arches, between the eight receding 

 rhopalar incisions of the umbrella margin. Between each two rhopalia there are eight 



