MEDUSJE. 35 



formalin and shows no sign of shrinkage, but the length and narrowness of the umbrella 

 are no doubt due to contraction at the moment of death. The stomach is very short 

 and quadrilateral. The gonads contain fairly large ova and are evidently about ripe. 

 They occupy the central third of the radial canal and are cylindrical in shape. The 

 curious feature of this specimen is that it has only three little degenerate-looking 

 tentacles. The margin of the umbrella looks quite perfect and shows no signs of 

 damage. There are eight sensory pits, two in each quadrant. Although the margin 

 looks perfect, yet it has an unnatural appearance. The presence of one interradial and 

 two perradial tentacles, without any marginal bulbs, rather indicates that the normal 

 course of development has not taken place. 



Localities.' Discovery ' Coll.; 3. ix. 02; Lat. 66 52' S., long. 178 15' E. 

 'Discovery' Coll.; 16. iii. 03 and May, 1903; Winter Quarters, McMurdo Sound. 

 'Southern Cross' Coll.; 27. xi. 99; Cape Adare ; Surface temp. 28 9' F. 



COSMETIRA FRIGIDA. 



For the generic characters, see p. 32. 



In the ' Discovery ' collection there are several specimens of a Leptomedusa with 

 tentacles, cirri, and traces of open sensory pits. All the specimens are in bad condition 

 and it is impossible to give a satisfactory account of them, or a trustworthy drawing. 

 As the exact number of sense organs remains unknown, this species is placed 

 provisionally in the genus Cosmetira. 



Description of the Species. The umbrella is probably hemispherical in shape, with 

 fairly thin walls. The largest specimen measures about 7 mm. in height and 10 mm. 

 in width. The stomach is fairly large, with a cross-shaped base attached to the radial 

 canals. The mouth is large and its margin is slightly folded. Four broad radial canals 

 and a broad circular canal. The gonads extend along nearly the whole length of the 

 radial canals, but not over the proximal and distal ends of the canals. They are band- 

 shaped and hang down in folds. There are about thirty-two tentacles, fairly long and 

 covered with transverse rows of nematocysts. Their basal bulbs are long, hollow and 

 tapering, and slightly compressed laterally. Between every two tentacles there are 

 numerous long cirri, some of which are situated on the side of the ex-umbrella, just a 

 little way above the margin. The cirri have a minute, oval, terminal cluster of 

 nematocysts. 



The above description is based upon the best specimen, in which sense organs 

 could not be detected. But three smaller specimens, which evidently belong to the 

 same species, do show sense organs. They are open sensory pits with the aperture 

 situated upon the inner side of the velum. The species has probably eight sense 

 organs, which from their size should contain several otocysts. 



There are four other specimens which may belong to the same species. They have 

 smaller tentacles and basal bulbs, and their gonads are over the outer half of the radial 

 canals. They also have cirri and open sensory pits. 



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