60 MR JAMES RITCHIE : SUPPLEMENTARY REPORT ON 



JMeasurements (a and h are distinct colonies) : — 



Locality. — Creeping on gulf weed, lat. 27° 54' 



N., long. 33° 17' W. 28th -Tune 



1904. 



Sertularia opei-culata, Linnaeus, 1758. 



Several small fragments of this species occur intertwined with other Hydroids from 

 the same locality. The specimens are typical in branching and in minute structure, 

 but a considerable amount of variation occurs not only in the length of the two 

 hydrothecal teeth, but also in their prominence relative to each other {cf. Hartlaub, 

 1905, pp. 665, 666). Of the specimens figured by Professor Hartlaub our examples 

 most nearly approach those from West Patagonia collected l^y F. P. Moreno ; but from 

 those they differ in the proximity of the hydrothecae, for the teeth of one may reach 

 the level of the base of its successor. The present examples are also characterised by 

 the exceedingly minute portion of the distal extremity of the hydrotheca, which is free, 

 the proximal side of the aperture lying almost against the internode. 



The points above refer specially to the younger branches. On the older portions 

 the hydrothecae are only sub-opposite, their length is less relatively to that of the 

 internode, while a slightly longer distal portion is free. 



A few typical gonangia occur on the branches. They exhibit a tendency to 

 asymmetry, the aperture lying towards the outer side of the axis of symmetry. 



The following measurements indicate the relations of the various parts : — 



Length of branch internode .... 0'33-0-50 mm. 



,, .stem internode .... O'o4-0'61 ,, 



„ hydrotheca ..... 0-20-0-2.T „ 



teeth ..... 0-06-01-2 „ 



Distance from tip to tip of a hydrntlieca-pair . . 0-43-0-58 „ 



Locality. — Dredged at the entrance to Saldanha Bay, Cape Colony, in 25 fathoms. 

 21st May 1904. 



The distribution of this species is world-wide. In addition to its European localities 

 it has been recorded from the coasts of North and South America, of Southern Asia, of 

 Australia and New Zealand, and of Africa, although the records from the last continent 

 are few. The African localities other than the Scotia record are as follows : — 



South Africa (Busk, 1850) ; Cape of Good Hope {Eugenie Expedition, Jadkrholm, 

 1903); Port Natal (Professor J. A. Wahlberg, Jaderholm, 1903); Mauritanian Coast 

 (Billard, 1906<'>); North-West of Cape Blanc, Soudan (Billard, 1906'"). 



(ROY. SOC. EDIN. TRANS., VOL. .XLVII., 82.) 



