70 MR JAMES RITCHIE 



characteristic ringing of C. Hinksii, where the first annulation is included in the base of 

 the hydrotheca. From C. cylindrica, Allm., and C. tincta, Allm., it is also distinguished 

 by its campanulate form and its peduncle characters. 



Obelia geniculata, Linnaeus, 1758. 



Several specimens of this well-marked species were obtained growing on the fronds 

 of a large seaweed Macrocystis pyrifera. 



The hydrotheca-bearing shoots, which are generally simple and average only 12 mm. 

 in height, arise from a creeping stolon which ramifies over the surface of the seaweed 

 frond. The trophosome agrees with the description in HINKS'S British Hydroid 

 Zoophytes, but here the annulations on the peduncle are rather more variable two or 

 three as well as a larger number being common. Within the hydrotheca, a short 

 distance from the base, a perisarcal ridge is well marked, supporting the flattened 

 basal portion of the polyp. Just above this bracket there occurs an irregular ring of 

 minute refringent spots small prominences on the inner side of the hydrotheca wall to 

 which the basal disc of the polyp is attached. These prominences resemble and serve 

 the same purpose as those found throughout the genus Halecium (vide p. 525). The 

 polyps are well preserved, and show well the large, trumpet-shaped proboscis. 



Gonosome. Absent. 



Locality, etc. Growing on the fronds of Macrocystis pyrifera, Gough Island. Lat., 

 40 20' S. ; long., 9 56' W. Date, 22nd April 1904. 



Obelia longissima, Pallas, 1766. 



A large number of weather-beaten colonies were found in the South Orkneys. The 

 specimens are about 8 cm. high and agree closely with HINKS'S description and figures. 

 The hydrothecse are mostly awanting ; those which remain are fragile and much 

 crushed, and probably as a consequence I was unable to detect the blunt teeth which 

 mark the rim. The pedicels, which taper towards the top, are usually altogether ringed, 

 but sometimes only in the proximal and distal regions, the median portion being smooth. 

 A pedicel was frequently noted springing from the axil between branch and branchlet, 

 as mentioned by HINKS (1868). 



Subsequent specimens, residue from the seaweed collections, were in better 

 condition. 



Gonosome. Wanting. 



Localities, etc. (a) Macdougall Bay, South Orkneys. November 1903. (b) Off rocks 

 in shore-pool, Scotia Bay, South Orkneys. Temperature, 30 to 32. Date, 6th December 

 1903. 



The specimens from both localities appear to have been exposed to weathering for 

 some time. Those from (b) especially show traces of rough usage, the branches being 



(EOT. soc. EDIN. TRANS., VOL. XLV., 528.) 



