376 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



OPERCULINA BARTSCHI, new species. 



Description. — -Test comparatively large, compressed except in the 

 central region, coils rapidly widening; central portion thickened, 

 biconvex, composed of several coiled chambers, and ornamented on 

 the sm*facc with numerous comparatively large bosses; chambers 

 numerous, 20 to 25 in the last-formed coil; curved sutures distinct, 

 not ornamented, but the chambers between with numerous compar- 

 atively large granulations, usually in somewhat definite lines across 

 the test. 



Diameter up to 8 mm. 



Distribution. — T3'pe specimen (Cat. No. 15848, U.S.N.M.) from 

 Albatross station D5134 Sulu Archipelago, near Basilan Island, 25 

 fathoms (46 meters). 



This has occurred at several stations in the area, as follows: China 

 Sea, off southern Luzon; Sulu Sea, off western Mindanao; vicinity 



of Jolo; vicinity of Siasi; Tawi Tawi Group; 

 off Romblon; between Pana}^ and Negros; off 

 northern Cebu; Sogod Bay, southern Leyte; 

 Pacific Ocean, east coast of Mindanao; Gulf 

 of Davao; Linapacan Strait; Palawan Pas- 

 sage; between Cebu and Boho; eastern 

 Palawan and vicinity; east coast of Luzon; 

 between Leyte and Mindanao; northern 

 Mindanao and vicinity; between Negros and 

 Siquijor; north of Tawi Tawi; and Buton 

 Strait. 



This is evidently one of the varieties de- 

 scribed by Carpenter from the Philippines. 

 It seems to be one of the most common 

 species of the Albatross collection from the 

 Philippine area, and has two definite varieties, which are here indi- 

 cated. It is closely related to the granular forms of Heterostegina 

 which were found in this material. 



It is named in honor of Dr. Paul Bartsch, of the United States 

 National Museum, whose careful collecting while in charge of the 

 Philippine Expedition has been responsible for such abundant series 

 of specimens. 



There is a local race of this species found at two stations, D5640 

 and D5642, both from Biiton Strait. These have a thickened 

 periphery and larger size than the typical form. The granules of 

 the exterior are smaller than the area farther north. 



Fig. 13.— Operculina baktschi, 

 NEW SPECIES. Side view, X 15. 

 Feom station D5134. 



