38 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



constrictions and rapidly tapering arms also being distinctive char- 

 acters. It was found only in this restricted region south of the 

 Equator. 



Rhabdammina abyssorum, var. radiata — Material examined. 



RHABDAMMINA IRREGULARIS W. B. Carpenter. 



Plate 1, fig. 5. 



Rhabdammina irregularis W. B. Carpenter, Proc. Roy. Soc. London, vol. 18, 

 1869, p. 60.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 268. 

 pi. 21, fig. 9.— CusHMAN, Bull. 71, U. S. Nat. Mus., 1910, pt. 1, p. 26, figi^. II, 12 

 (in text); Bull. 104, U. S. Nat. Mua., 1918, pt. 1, p. 17, pi. 8, fig. 1. 



In the region along the Equator and southward in the Gulf of 

 Boni, Flores Sea, and Buton Strait this species is frequent at depths 

 ranging from 24 to 1,560 fathoms (44 to 2,853 meters). It occurred 

 at 20 stations in this area, the bottom temperatures, where given, 

 ranging from 36.3° to 52.3° F. (2.3° C. to 11.2° C). In one lot of 

 material from D5385, Ragay Gulf, Luzon, 327 fathoms (598 meters), 

 this species occurred with the bottom temperature recorded as 62.4° F. 

 (16.8° C). At some stations the great mass of the dredged material 

 consisted of this species which was very similar to that from the Gulf 

 of California. Some of the specimens show two sets of branches 

 nearly an inch apart. Although the material was dredged in quan- 

 tity it adds little to the knowledge of the structure or the initial por- 

 tion of the test of this species. Evidently, as previously noted, there 

 is a point of weakness just above the place of branching where the 

 process of dredging seems sure to break the specimen. The following 

 localities, mostly in the southern part of the region in deep v/ater, 

 had this species: Ragay Gulf, Luzon; between Gillolo and Makyan 

 Islands; Buton Strait; Sibuko Bay, Borneo; between Gillolo and 

 Kayoa Islands; Gulf of Boni; north of Celebes; Patiente Strait; and 

 Flores Sea. 



