1010.] FROM MERGUI ARCHIPELAGO. 811} 



North Atlantic Ocean, and from the Western Pacific (China ami 

 Eastern Australia), it has not hitlunto l^ecn found in the Indian 

 Ocean. 



Calycella oligista *, sp. n, (Plate LXXVI. figs. 3 ik 4.) 



Trophosome. The colony is epizoic, and consists of a creepina", 

 delicate stolon which lies in close contact with the specimen upon 

 which it occurs. Prom this stolon hydrothecie spring at irregular 

 intervals. 



The hydrotheciv are exceedingly minute, delicate, hyaline, and 

 transparent, without a trace of the smoky tint which charac- 

 terises (,'. syringa. In shape they are tubular and cylindrical, of 

 approximately the same diameter for the greater portion of their 

 length, although the proximal half is usually slightly bulged, and 

 tapers, more or less rapidly, to join the stalk. The mai'gin of the 

 hydrotheca, which is very slightly everted, is definite, and is of 

 considerable strength, for it is seldom that it is found in a 

 collapsed condition. It is divided into shallow crenulations, 

 similar to those in C. syringa, each of which subtends the base of 

 an opercular valve. In no case was a duplication of the margin 

 noticed. The operculum is distinct from the hydrothecal wall, 

 and is composed of al)out twelve to fourteen exceedingly delicate 

 valves, ditficult to distinguish. The cavity of the hydrotheca is 

 separated from that of the stalk by a distinct but delicate 

 diaphragm. The stalk is usuall}^ very short, so that the hvdro- 

 theca almost rests on the stolon, but in one case (PI. LXXVL 

 fig. 3) a well developed stalk was observed. This stalk was marked 

 by a few irregular indentations, but in other cases the stalks were 

 smooth, and ringing of a regular nature never occurred. 



The hydranth is large compared with the size of the hydrotheca. 

 It is attached by a basal disk to the hydi-othecal wall immediately 

 above the diaphragm, and is continued upwards as a cylindrical 

 body with conical hypostome, surrounded by a whorl of about 

 seven to ten tentacles. The ectoderm is thick, and the tentacles, 

 in contraction, are dumpy and stoat. 



The gonosome was not observed. 



Dimensions : — 



Stolon, diameter , 30 «,. 



Hydrotheca, depth 120-138 ;tt. 



,, greatest diameter 45-66 /a. 



Localities. St, 23, Five Islands, 8 to 12 fathoms, rock and sand, 

 and mud ; very rare, on Idia pristis. St. 35, between Warden 

 Island, Howe Island, and Lyall Island, 15 to 20 fathoms, rock 

 and sand ; veiy rare, on Idia pristis and Thyroscyphas vitiensis. 



Systematic positio7i. — This species difiei's remarkably in size, 

 colour, texture, and in the development of the pedmicle and its 

 ringing from C. syringa, although there is a similarity between 



* oXIyiaro^, smallest. 



Proc. Zool. Soc— 1910, No. LIII. 53 



