804 SIR- J- RITCHIE ON- HYDROIDS [May 2-t, 



Family B o c G A i s v i l L I D .E. 



Perigosimus kepess Wright, 1858. 



Rare examples of an epizoic species occur, wLicli cannot be 

 specifically distinguished from British specimens of P. repens, 

 the simple lax habit of which they exactly assume. There 

 are dLffei-ences between the dimensions of the Mergui and of 

 British examples ; for whOe the former are smaller in height 

 and in the proportions of their hydi-anths and hydrocaulus, in 

 respect of the nematocysts in the tentacles the order is reversed. 

 The compai-ative table which follows shows at a glance the size- 

 relations of the two forms. About twelve tentacles cro^-n each 

 hydi-anth. 



No trace of gonosome was observed. 



Dimensions : — ilergui Typical Scottish 



specimen. example *. 



Height of colony 3 mm. 6 mm. 



Diameter of hydrocaulus 0'04 mm. 0'07 mm. 



Hydi-anth, length 0-17-0-24mm. 0-24-0-34mm. 



„ greatest breadth 0-08-0-13 mm. 014-0-15mm. 



Xematocysts of tentacles, length 5"5 /x. 4'5 /x. 



„ „ breadth 3 /j.. 2'2 /i. 



Locality. Rare colonies epizoic on Cori/denclrium sessile, from 

 St. 3.5, between Warden Island, Howe Island, and LyaU Island, 

 1.5 to 20 fathoms, rock and sand. 



The present record adds P. repeyis to the fauna of the Indian 

 Ocean. It has already been noted from the eastern and western 

 sides of the North, and the western side of the South Atlantic 

 Ocean, from the Mediterranean Sea, and from the eastern and 

 western (Japan: Stechow, 1909, p. 25) sides of the Pacific Ocean. 



Family Eudendrid^. 



EuDEXDRiuM ATTExuATUSi Allman (?), 1877. 



Many poor colonies, lacking any trace of hydranth or gono- 

 some, I refer, with uncertainty, to this species, on account of 

 resemblance in the skeleton. The Mergui specimens attain a 

 somewhat gi-eater length (3 inches) than the original examples ; 

 but the delicate, very slender, non-fascicled stems, with their few 

 branches, and their short hydranth-bearing ramules lying in one 

 plane and set alternately at legular intervals of about 1 mm., are 

 very similar in both cases. Three or four rather irregular annu- 

 lations mark the base of each ramule, and occasionall)' a few odd 

 rings occur irregularly on the ramules and on the stem itself. 

 The regiUar and close alternation of the hydmnth-bearing ramules 

 seems the most evident character of an indefinite species, though 

 a somewhat similar arrangement is observed in E. maldivense 

 Borradaile (1905, p. 838). 



* Slide of specimen from Loch Carron, 60 fathoms, in my collection. 



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