MEDUSA. 



43 



December, 1899, and January, 1900. The ice was then breaking up and departing 

 from the coast. The temperature of the sea at the surface was 29 to 30 F. These 

 specimens were evidently ruined by bad storage. It is sad to see large specimens in 

 such an unsatisfactory condition, especially when the correct determination of the 

 species is of importance. 



The 'Discovery' obtained a single specimen on 1st August, 1902. It was 

 captured by hand in MrMurdo Sound. This specimen also got broken into pieces. 



The occurrence of Pei-i/ilii/Un at or near the surface in the icy Antarctic region is 

 very interesting, because it is not a surface-seeking Medusa in the Atlantic or Pacific, 

 but prefers to inhabit the intermediate and deeper zones of those oceans. I have but 

 little doubt, from the appearance and condition of the internal organs, that these 

 specimens were alive and in healthy condition when taken out of the sea ; and that 

 they were not dying specimens, as Vanhoffen has suggested, or ones washed up from 

 the depths of the Antarctic Ocean. 



Haeckel, from the material collected by the ' Challenger,' described and figured in 

 great detail tvo new species of Periphylla, namely, P. mirabilis, of which a single 

 specimen was taken in lat. 40 28' S., long. 177 43' E. (off the east coast of New 

 Zealand) ; and P. rc/jina, a single specimen of which was found south-west of the 

 Kerguelen Islands (lat. 62 26' S., long. 95 44' E.). 



Messrs. Maas and Vanhoffen recognise three species of Periphylla, namely, 

 P. hyacinthina, Steenstrup, /*. dodecabostrycha (Brandt), and P. regina (Haeckel). 



Periphylla mirabilis is considered by Maas (1897) and by Vanhoffen (1902) to be 

 identical with P. dodecabostrycha. 



According to Prof. Haeckel's description and figures, the rhopaliar pedalia of 

 P. mirabilis are shorter than the tentacular ones. It seems to me that he has divided 

 the rhopaliar pedalia into two parts by a transverse groove. In the ' Challenger ' type 

 specimen of P. mirabilis the groove is more like a crease on the surface of the jelly 

 than a natural groove. If one disregards this crease, then the rhopaliar pedalia are 

 longer than the tentacular pedalia, and are similar in shape to those on the specimens 

 in the two Antarctic collections, and also similar to the pedalia of P. hyacinthina 

 (Haeckel, 1880, Taf. xxiv.). 



The ' Challenger ' type specimen of P. regina in the British Museum consists of 

 a few fragments. From a scientific point of view these fragments are of little value, 

 and can now be looked at only as objects of historical interest. 



The description and figures of P. dodecabostrycha, as first given by Brandt (1838). 

 are based upon a large specimen about 200 mm. in length and width. The specimens 

 taken by the recent exploring expeditious have usually been small ones, not larger 

 than 27 mm. in height and 18 mm. in width. Mr. Bigelow (1909) has put 

 forward good reasons for regarding the small specimens of P. dodecabostrycha, 

 described by Messrs. Mass and Vanhoffen, as young and less pigmented forms 

 of P. hyacinthina. 



VOL. V. 



12 B 



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