J.84 MR EDWARD T. BROWNE ON 



In the Voyage of the Scotia, a book which gives an interesting and popular account 

 of the work done by the Scottish National Antarctic Expedition, there is an allusion 

 to this medusa: "On the 28th, in 33 51' S., 48 48' W., we crossed a great yellow 

 band of gelatinous scum stretching from horizon to horizon. It proved to consist of 

 microscopic algse (Desmidae) closely allied to the diatoms, and in the scum were numbers 

 of Portuguese men-of-war (Physalia), Jelly-fish (Aurelia), Ctenophores, and other 

 organisms." The specimen was labelled Aurelia sp. 



Description. The umbrella has flattened out, and as it lies in the dish it is about 

 five times as broad as high. The diameter, measured across to the circular canal, is 

 about 120 mm. The central portion of the ex-umbrella is slightly raised and is covered 

 with small warts, which are quite visible to the naked eye. The periphery of the 

 umbrella is quite smooth. The base of the stomach is small for the size of the 

 umbrella, measuring only 30 mm. in diameter. The oral arms have disappeared, and 

 only broken stumps remain. 



From the stomach to the circular canal run forty-two broad radial canals. The 

 canals in the radii of the sense-organs are branched ; the branching is rather irregular, 

 and there is a tendency to anastomosis (fig. 3). The canals in the radii of the tentacles 

 are unbranched, with somewhat irregular outlines. 



The margin of the umbrella is not quite perfect, but nine sense-organs are present, 

 and the number of branched radial canals indicates that two sense-organs are missing. 

 The tentacles are arranged in a single row along the outer edge of the circular canal. 

 The row is broken by the sense-organs so that groups are formed. 



The character of the genus Phacellophora is the presence of sixteen sense-organs, 

 by which it is distinguished from Sthenonia with eight sense-organs. The Scotia 

 specimen has eleven sense-organs and eleven groups of tentacles, and it is evident from 

 the irregular distribution of the sense-organs that the specimen is an abnormal one. 

 In two places on the margin the sense-organs are very close together, with just a few 

 tentacles between them. 



There are twenty tentacles in the largest group, and a very small tentacular bud 

 lies between every two tentacles. The tentacles are all about the same size and have 

 a well-marked character. They have the appearance of long, tapering threads of clear 

 jelly, with a thin whitish line along the outer side. On applying higher magnification 

 one sees that the tentacle has a canal running along its whole length. This canal in 

 the basal portion of the tentacle is very large, forming a large hollow cavity ; but it 

 quickly decreases in size until it becomes a very tiny tube, which is perhaps solid 

 towards the distal end, running not in the centre of the tentacle, but close against the 

 outer side (fig. 4). It is only the basal portion of the tentacle that is really hollow, 

 and the canal is a rudiment of an axial endodermal cavity. Along the outer side of 

 the tentacle runs a double row of warts, which are loaded with nematocysts. There 

 are no muscle-fibres visible in the tentacles. 



The ocular lobes (fig. 3) on the margin of the umbrella are thick, being flat on the 



(ROY. soc. EDIN. TRANS., VOL. XLVI., 248.) 



