822 MR. J. RITCHIE ON HTDEOiDs [May 24, 



In the structure of the operculum (S'. turhinata appears to 

 differ from S. versUujsi Nutting (1904) — regarded by Billard 

 (1908) as a synonym — for in the latter, as Congdon states (1907, 

 p. 482), and as careful examination of the lateral aspect of speci- 

 mens from Cape Verde Islands, in my collection, shows, the 

 operculum is furnished with a large abcauline and two smaller 

 latero-adcauline valves. 



The protractor of the hydranth, which possesses onl}' a small 

 blind-sac, is attached to the hydrotheoal wall at the intrathecal 

 ridge. 



Localities. Stt. 15 and 16, Ravenshaw Island, Sir John Malcolm 

 Island, and Alligator Rock, 5 to 18 fathoms, rock and sand, or 

 rock and mud ; not common. 



Family Plumularid.e. 



Plumulakia setacea Linnseus, 1758 (?). 



A single immature colony, 15 mm. high, identical in all respects 

 with North Sea specimens. I have written the designation with 

 a mai'k of interrogation on account of the impossibility of dis- 

 tinguishing the trophosome of this small variety fi'om that of 

 P. strictocarpa Pictet (1893), from Amboyna. 



Locality. Moskos Islands, 3 to 26 fathoms, rock and sand, or 

 rock and mud. 



Plumularia sp. 



An unidentifiable fragment, the structures of the stem and 

 hydroclades of which resemble those of P. setacea, but the frag- 

 ment shows traces of branching, and the hydrotheca of having 

 a slightly concave contour. 



Locality. St. 32, Hastings Harbour, shore to 20 fathoms, rock 

 and sand. 



Antenella secundaria Gmelin, 1788-93. 



The nematocysts of the nematophores measure 12 ^ by 4 /j, 

 agreeing with Warren's measurements of those in A. natalensis, 

 which I regard as a synonym. There are about 18 tentacles. 



Locality. St. 1, east of Tavoy Island and Port Owen, 4 to 12 

 fathoms, sand and broken shells, and mud ; not common, on 

 Idia pi'istis. 



Lytocarpus pexnaeius LinnsBus, 1758. 



A widely distributed species, represented by several fine 

 colonies, one of which reached a height of 95 cm. Apart from 

 the prominent anterior tooth, th.at on the margin of thehydro- 

 theca second from the stem is distinctly the largest. It forms 

 the highest point on the outwardly curved margin of the hydro- 

 theca. There is, however, some variation in the prominence of 

 [24] 



