384 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Operculina venom — Material exnmmed. 



Locality. 



14 23 55 N. 



6 44 45 N. 



6 06 00 N. 



6 06 00 N. 



6 09 00 N. 



6 06 10 N. 



6 05 50 N. 



G 05 50 N. 



6 04 30 N. 



5 41 40 N. 



5 35 40 N. 



5 33 00 N. 



5 22 55 N. 



5 14 .50 N. 



5 11 50 N. 

 12 43 00 N. 



12 38 15 N. 

 11 09 15 N. 

 10 10 00 N. 



13 11 15 N. 



120 32 33 E. 



121 48 00 E. 



120 58 50 E. 



121 02 .30 E. 



120 58 00 E. 



121 02 40 E. 

 121 02 15 E. 



121 02 15 E. 

 120 59 30 E. 

 120 47 10 E. 

 120 47 30 E. 

 120 42 10 E. 

 120 15 45 E. 

 119 .58 45 E. 

 119 54 00 E. 



122 06 15 E. 



122 l'^ 30 E. 



123 50 00 E. 

 125 04 15 E. 

 123 02 45 E. 



tem- 

 pera- 

 ture. 



fath- 

 oms. 



37 

 25 

 19 

 20 

 29 

 21 

 19 

 19 

 23 

 21 

 21 

 10 

 34 

 12 

 10 

 78 

 37 

 32 

 554 

 20 



75.7 



'si's" 



Character of 



bottom. 



gy-ni. 

 fne. s . 

 s.,co. 



C0..S 



I co.s 



I CO..S 



I CO.S 



I co.s 



co.s.jSh 



CO. s.,sh 



co.s.jSh 



co.s.,sh 



wh.s 



co.s 



CO. s 



fno. s 



hrd. s 



Kn.s 



gy.s.,m 



crs. s 



Abundance. 



Common. 



Common. 



Common. 



R^ire. 



Common. 



Common. 



Common. 



Common. 



Common. 



Few. 



Few. 



Few. 



Few. 



Common. 



Conmion. 



Rare. 



Rare. 



Rare. 



Rare. 



Rare. 



Genus HETEROSTEGINA d'Orbigny, 1826. 



This genus, which is comparatively abundant in certain parts of 

 the area, especially in the region of the Sulu Archipelago, is not repre- 

 sented by the usual species of the genus, but by two other forms, one 

 of which is very abundant and grows to a large size. 



HETEROSTEGINA DEPBESSA d'Orbigny, var. TUBERCALATA Moeblus. 



Heterostegina tnhercalata Moebtjis, Beitr. Meeresfauna Insel Mauritius, 1880, 

 p. 107, pi. 12, figs. 3-7. 



This variety differs from the typical form of the species in that the 

 earlier portion has numerous fine tubercles scattered over the surface; 

 usually also the central portion is slightly thickened, the remaining 

 part of the test being flat and complanate. None of the specimens 

 show the typical smooth form which is characteristic of the typical 

 form of the species. The t3"pes of d'Orbigny 's //. depressa were from 

 the Island of St. Helena. 



This variety was especially abundant at Alhatross station D5152, 

 in 34 fathoms (62 meters), off Tawi Tawi group, Sulu Archipelago. 

 It has also occurred in the following localities: Sogod Bay, southern 

 Leyte; China Sea, off southern Luzon; and between Negros and 

 Siquijor. It is only abundant in shallow water, the deeper stations 

 being represented usually by single specimens. Moebius described 

 this form from the shallow water of Mauritius. 



