1910.] FROM MEUGUI ARCHIPELAGO. 821 



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

 fathoms, sand and broken shells, and mud ; common. St, 14, 

 Bushby Island pearlinof-ground, shore to 21 fathoms, sand and 

 mud; common. Stt. 15 and 16, RaA'enshaw Island, Sir John 

 Malcolm Island, and Alligator Rock, 5 to 18 fathoms, rock and 

 sand, or rock and mud ; common. St. 22, Hastings Harbour, 

 shore to 20 fathoms, rock and sand ; common, with gonangia, 

 some colonies growing on a sponge. St. 23, Five Islands, 8 to 

 12 fathoms, rock and sand, and mud; fairly common. St. 25, 

 Gregory Group and Crichton Island, 4 to 14 fathoms, stones and 

 broken shells and rock ; common. St. 35, between Warden 

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

 and sand ; one colony. Moskos Islands, 3 to 26 fathoms, I'ock 

 and sand, or rock and mud ; common, with gonangia. 



DiPHAsiA DIGITALIS Busk, 1852. 



In these specimens it is clearly seen that the two so-called 

 opercular muscles are attached, not to the valves of the operculum, 

 but to the lateral walls of the hydrotheca near the margin, and 

 are, in function, protractor muscles (see Nutting, 1904, p. 13, 

 fig. 17). The hydranth possesses about twenty tentacles. 



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

 fathoms, sand and broken shells, and mud ; several small colonies, 

 on the bare axis of an Alcyonarian, and on Idia pristis. 



Recorded from the Western Indian Ocean — Maldive Islands — 

 by Borradaile (1905, p. 842) ; this is the first record from the 

 Eastern Indian Ocean. 



Sertularia turbinata Lamouroux, 1816. 



{ = 6'. loculosa Busk 1852 *.) 



Several small, unbranched colonies of this species occur upon 

 ThyroscypMis ritiensis. They are pale in colour, in this, as well 

 as in the shortness of the internodes, agreeing with the specimens 

 described from Paumben, India, by Jiiderholm (1903). But they 

 diflfer in the reduction of the lateral teeth, which are occasionally 

 so indistinct that the aperture appears to be almost round. 

 Besides an indistinct tooth on each flank, the hydi'otheca is 

 surmounted by a small third tooth, from the summit of which a 

 membranaceous ex^gQ sometimes runs to the lateial teeth. Not- 

 withstanding difticulties of observation, I feel assured, after 

 examining many liydrothecje, that the operculum is foimed of a 

 solitary flap, hinged on the distal edge of a slight thickening 

 which occurs on the abcauline margin of the hydrotheca. 

 Although membranes unite the superior with the lateral teeth, 

 these do not hinge inwards, and can scarcely, therefore, be 

 accounted part of the opei'culum. They are the less necessary 

 since the abcauline flap is of diameter sufficient completely to 

 close the apei'ture of the hydrotheca. 



* Fide Billard (1909, p. 322), who has examined the type specimen of Lamouroux. 



