292 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



small round avicularia without pivot. On the basal fronds, groups 

 of smooth zooecia more or less erect, arranged without order appear. 

 The oral avicularium opens in the peristomie, it is little visible. 

 The oral glands have been well described by Waters, 1909. 



We are not in accord with Waters on the details of the operculum. 

 We possess many preparations containing a dozen opercula all quite 

 similar to those we describe. 



Biology. — This is a tropical species. It lives in waters of from 

 19 to 24 fathoms; but it can descend deeper, because we have found 

 it at Tinagta at 230 fathoms. The sandy, coralline, and shelly bot- 

 toms suit it especially well. The thickness of the fronds increases 

 with depth. 



Almost all our specimens were dead. Those from Sirun were 

 living; they were in reproduction February 16, 1908 (37 meters). 



A B 



C -D 



Fig. 122. — Cigclisula occlusa Busk, 1884 



A. Operculum of abnormal zooecium, X85. B. Mandible of inverted avi- 

 cularium, X85. C, D. Two forms of opercula, X85. 



Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E. 



20 fathoms; S. Sh. 

 D. 5144. Jolo Light, Jolo; 6° 05' 50" N.; 121° 02' 15" E. 



19 fathoms; co. S. 

 D. 5145. Jolo Light, Jolo; 6° 04' 30" N.; 120° 59' 30" E. 



23 fathoms; co. S., Sh. 

 D. 5150. Sirun Island, Sulu Archipelago; 5° 23' 20" N.; 120° 



35' 45" E.; 21 fathoms; co. S., Sh. 

 D. 5151. Sirun Island, Sulu Archipelago; 5° 24' 40" N.j 120° 



27' 15" E.; 24 fathoms; co. S., Sh. 

 D. 5162. Tinagta Island, Tawi Tawi Group; 5° 10' N.; 119° 



47' 30" E.; 230 fathoms; S. brk. Sh. crs. 

 D. 5478. Tacbuc Point, Leyte; 10° 46' 24" N.; 125° 16' 30" E.; 

 57 fathoms; Sh. 

 Geographic distribution. — Pacific: Crozet Island, 210 fathoms; Cape 

 York, 8 fathoms; Simboangan, 10 fathoms; Albany Pass, 10 fathoms, 

 and Murray Islands, 15-20 fathoms; Torres Strait, Cape Jaubert, 

 Australia. Indian Ocean: Wasin, British .East Africa, 10 fathoms; 

 Ras Osowemembe, Zanzibar Channel, 10 fathoms; Bay of Agig 

 Suraga, South Sudan coast. 



Plesiotypes. —Cat. No. 8037-8040, U.S.N.M. 



