THE MEDUSA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 245 



Specimen B (Vallentin Coll.). — The umbrella is fairly thin and flat, measuring 

 about 25 mm. in diameter, and is very pellucid in formalin. 



The stomach is about 15 mm. in diameter, with sixteen radial pouches. The 

 tentacular pouches are a little broader than the ocular ones. The oral arms are about 

 twice as long as the radius of the umbrella. 



The tentacles show an increase in number and in size. In each group the central 

 tentacle is very conspicuous by its great length (fig. 2). It is at least six times as 

 long as the other tentacles. Each group contains about three to six tentacles and 

 about six tentacular buds. 



The cleft in the middle of the tentacular lobe has nearly disappeared (fig. 2), and 

 the ocular lobes are just marked off by a slight incurving of the margin. Each ocular 

 lobe has a broad canal which gives off a number of short lateral branches, which in this 

 stage are just beginning to develop. The tentacular lobes have a number of canals, 

 one between every two tentacles. These canals in the later stages have each a series 

 of bifurcations. 



Specimen C [Scotia Coll.). — The umbrella is moderately curved and is fairly thick, 

 measuring 50 mm. in width and 20 mm. in height. 



The stomach is circular, about 25 mm. in diameter, with sixteen radiating pouches. 

 The width of the tentacular pouches at their distal end is about 10 mm., and the ocular 

 pouches about 7 mm. The oral arms are in a damaged condition. The width between 

 the pillars of the arms, measured across the oval where the gonads are just beginning 

 to show, is 11 mm., and the width of the pillar is 3 mm. at its narrowest point. 



There are eight groups of tentacles arranged in a straight single row. Each group 

 consists of twelve to fifteen tentacles, with the largest in the middle. The large 

 tentacles are all in a broken condition. 



The cleft in the middle of the tentacular lobes has practically disappeared. The 

 ocular lobes are slightly more prominent, projecting further out than the tentacular 

 lobes. The canal system is of the same pattern as in specimen B, but the branches 

 have more bifurcations. 



Specimen D. — The umbrella is fairly thick, about 80 mm. in width and 40 mm. in 

 height. Clusters of nematocysts are closely scattered over the ex-umbrella and the 

 marginal lobes, but the warts are absent, so that the surface looks quite smooth. 



The stomach measures about 35 mm. in diameter. The width of the tentacular 

 pouches at the distal end is about 18 mm., and the ocular about 12 mm. This speci- 

 men is in a damaged condition, having lost its oral arms, gonads, and tentacles. The 

 distance between the pillars of the oral arms is about 15 mm. There are indications of 

 twelve to fourteen tentacles in each of the eight groups. 



The ocular and tentacular lobes are united into one large lobe with an even margin. 

 The marginal distinction between the lobes has become obliterated, and the medusa has 

 the appearance of possessing eight broad marginal lobes which are separated from each 

 other by the deep ocular clefts. But owing to the incurving of the margin of the 



