310 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Earland has shown the complicated structure of this species and 

 the peculiar adaptation of the "float chamber." It is found in 

 enormous numbers at certain times from the observations of several 

 collectors. Records show that it is well scattered through the Indo- 

 Pacific region, eastward to the Hawaiian Islands, south to Australia, 

 and west to the coast of Africa. It is also recorded from the Medi- 

 terranean and from the West Indies. 



Tretomphalua bulloides — Material examined. 



Genus PLANORBULINA d'Orbigny, 1826. 



PLANORBULINA LARVATA Parker and Jones. 



PlanorbuUna vulgaris d'Orbigny, var. larvata Parker and Jones, Ann. Mag. 



Nat. Hiat., ser. 3, vol. 5, 1860, p. 294. 

 PlanorbuUna larvata Parker and Jones, Philos. Trans., vol. 155, 1865, p. 379, 



pi. 19, figs. 3a, b.—H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, 



p. 658, pi. 92, figs. 5, 6.— CusHMAN, Bull. 71, U. S. Nat. Mus., pt. 5, 1915, p. 



27, pi. 8, fig. 2. 



This species seems to be very clearly a tropical one, and is, as might 

 be expected, a very characteristic species of the Philippine Archi- 

 pelago, especially in comparatively shallow waters. Outside the 

 Archipelago proper it was noted in the material from the Gulf of 

 Boni; Buton Strait; Sibuko Bay and Darvel Bay, Borneo. The 

 numerous stations from the Archipelago give it a rather general dis- 

 tribution among the islands. The depths range from 17 to 805 

 fathoms (31 to 1,472 meters), with the average depth 177 fathoms 

 (324 meters). Bottom temperatures where given range from 38.3° 

 to 58.6° F. (3.5° to 14.7° C), with the average 49° F. (9.5° C). 

 These temperatures are really too low, as the bottom temperatures 

 are not given in many cases from the shallow-water stations. 



From the great mass of material available it would seem as though 

 this species clearly displaced P. mediterranensis in the Philippine 

 region, as this latter species was not found at all. 



