804 MR. J. RrrciiiE ox iiykroids [May 24, 



Family li o u g a i n v i l l i d .13. 



PERIGONIMUS REPEXS Wright, 1858. 



Rai-e examples of an epizoic species occur, which cannot be 

 specifically distinguished from IJritish specimens of P. repens, 

 the simple lax liabit of which tliey exactly assume. There 

 are differences between the dimensions of the Mergui nnd of 

 British examples ; for while the former are smaller in height 

 and in the proportions of their hydranths and hydrocaulus, in 

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

 The comparative table which follows shows at a glance the size- 

 relations of the two forms. About twelve tentacles crown each 

 hydranth. 



No trace of gonosome was observed. 



Dimensions : — IMeigui Typical Scottish 



specimen. ex:iini)lu *. 



Height of colony 3 mm. nun. 



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



Hydranth, length 0-17-0-24mm. 0-24-0-34 mm. 



„ greatest breadth 0-08-0'13 mm. O-U-O-l") mm. 



Nematocysts of tentacles, length 55 /a. 4*5 /a. 



„ „ breadth 3 //,. 2-2 /a. 



Locality/. Rare colonies epizoic on Cor}/dendrin.ia scasile, from 

 St. 35, between ^yarden Island, Howe Island, and Jjyall Island, 

 15 to 20 fathoms, rock and s;vnd. 



The present record adds P. repe.ns 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 E u d e n D u i d .e. 



EUDENDRIUM ATPENUATUM Albnan (?), 1877, 



Many poor colonies, lacking any trace of hydi'anth or gono- 

 .some, I refer, with uncertainty, to this s[)ecies, on account of 

 resemldance in the skeleton. The Mergui specimens attain a 

 somewhat greater 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 regular intervals of about 1 mm., are 

 v(M-v similar in both ca.ses. Three or four rather irregidar annu- 

 latious mark the base of each ramule, and occasionally a few odd 

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

 The regidai- and close alternation of the hydranth-bearing r.anndes 

 seems the most, evident chaivicter of an indefinite spi'cies, though 

 a somewhat similar arrangement is obscrveil in E. maldivense 

 Borradaile (1905, p. 838). 



* Slidi' f>f spetiuifcii fVoiii Loch I'lindii, (!(» IiiIIkhiis, in my collection. 



