HYDROMEDUSAE 293 



L. piilchra differs rather considerably from the other species of the genus, in general 

 appearance, in the shape of the stomach, and in the structure of the tentacles, particularly 

 of their basal parts. It bears a considerable resemblance to the more primitive species of 

 Ptychogena, P. californica Torrey (1909, p. 13) and P. crocea Kramp and Damas (1925, 

 p. 290, pi. 35), but the presence of ocelli on the basal bulbs separates it from the genus 

 Ptychogena. 



Family MITROCOMIDAE 



Genus Cosmetirella Browne (19 10) 



Generic characters. Mitrocomidae with four radial canals; with eight statocysts 

 without ocelli; without marginal cirri. 



Cosmetirella davisi (Browne) (Plate XVII, fig. i). 



Tiaropsis davisii Browne, 1902, p. 281. 

 Cosmetirella simplex Browne, 1910, p. 34, pi. i, figs. 6-8. 

 Phialella falklandica Vanhoffen, 191 1, p. 223, Taf. 22, fig. 10. 

 Cosmetirella kerguelensis Vanhoffen, 1912^, p. 368. 

 Cosmetirella simplex Vanhoffen, 19120, p. 368. 

 Cosmetirella davisi Kramp, 1932, p. 359, figs. 4, 34, 46. 

 Cosmetirella davisi Thiel, 1938, p. 327. 



An account of the history of this medusa was given by Kramp (1932), who also gave 

 a new description of the species and demonstrated the specific identity of Tiaropsis 

 davisi Browne, Cosmetirella simplex Browne, and C. kerguelensis Vanhoffen. This 

 result was obtained from an examination of the type specimens of Tiaropsis davisi and 

 Cosmetirella simplex, during a stay at Berkhamsted, and also of some specimens in the 

 British Museum, collected by the 'Discovery' in 1926 and 1927. A single specimen 

 from South Georgia is described by Thiel (1938). 



The following is a description of the largest specimen found at the Falkland Islands 

 (Plate XVII, fig. i): 



Umbrella somewhat conical, a little broader than high, with moderately thick walls. 

 Stomach small, cross-shaped when contracted. Mouth with four large fimbriated 

 lips. Gonads occupying nearly the whole length of the four radial canals, not touching 

 the stomach and not extending quite down to the margin of the umbrella, forming a 

 thin, narrow, simple band. Tentacles seventy-seven (thirty-five larger and forty-two 

 smaller ones), fairly short, with broad basal bulbs; nematocysts not in groups or rings. 

 Statocysts eight, adradial, fairly large. Size: 11 mm. in width and 8 mm. in height. 



The collection contains only three specimens, 9-1 1 mm. wide, taken in Stanley 

 Harbour on 10 November and 6 December 1898. The species is not represented in 

 Vallentin's second collection, 1901-2. The gonads in the largest specimen do not 

 appear to be mature. 



The species grows to a considerably larger size; the specimens collected by the 

 'Discovery' are 12-18 mm. wide, and those from Kerguelen Island, described by 

 Vanhoffen, measured 19-36 mm. in diameter. 



