133 DISCOVERY REPORTS 



Very rare, but a few excellent specimens both megalospheric and microspheric were 

 found at St. 386; two megalospheric specimens at St. 385. Both stations are in the deep, 

 water of the Drake Strait, 3638-4773 m. 



Genus Bolivina, d'Orbigny, 1839 



272. Bolivina punctata, d'Orbigny (F 143) (SG 177) (Plate VI, figs. 5-7). 

 Forty-five stations: 164, 171, 180, 181, i86, 190, 192, 195-9, 202, 203, 206, 366, 384-6; 62° 57' S, 



60° 20' 30" W; 64° 56' S, 64° 43' W; WS 204, 382-5, 391, 395, 396, 403, 471, 476, 479, 480, 482-7, 

 493. 494A, 509. 512, 513. 



Generally distributed, but varying greatly in numbers. It is very common at Sts. 

 WS 395, 485 and 487; common at Sts. 192, 196, 62° 57' S, 60° 20' W, and WS 486; 

 frequent at Sts. 195, 202, 203, 385, 386, WS 383, 384 and 483. All these stations are in 

 less than 1000 m., except Sts. 385 and 386, which are in the deep water of the Drake 

 Strait, over 3600 m. At the remaining stations the species is rare or very rare, and some- 

 times represented by a single specimen. Their depths range between 24 m. at St. 164 

 (a single specimen) and 3762 m. at St. WS 471 (also a single pauperate specimen), but the 

 majority are under 1000 m. Where the species occurs in any numbers both microspheric 

 and megalospheric specimens are found, the megalospheric predominating greatly in 

 numbers and being the only representative of the form at the stations where the species 

 is rare. There is no doubt that the species is trimorphic; although time has not per- 

 mitted of exact measurements there is a very noticeable difference in the size of the 

 megalosphere at various stations. 



A very curious pauperate (?) form occurs at several stations; in company with the 

 ordinary type at Sts. 171, 195, 203, WS 385, 483 and 485, by itself at Sts. 198 and 

 WS 471 . These stations cover almost the entire range of depth. In these specimens the 

 upper half of each chamber becomes so thin as to be iridescent and in many instances is 

 entirely wanting, the test then showing an outline of sharp cusps. I think the fact that 

 the pauperate specimens are usually found in company with the normal type is evidence 

 that the formation is incidental to the gradual solution of dead shells, the thinner portion 

 of the chamber being the first to disappear. On the other hand, it is rather singular that 

 other species do not show a similar tendency to the dissolution of one portion of the test 

 only. 



273. Bolivina textilarioides, Reuss (F 144) (SG 178). 



Eight stations: 164, 190, 195, 199, 366; Port Lockroy; WS 490, 512. 



Extremely rare, never more than one or two specimens at each station, and all very 

 pauperate. 



274. Bolivina spinescens, Cushman (F 145) (Plate VI, figs. 8-10). 

 Four stations: WS 505, 506, 507 a, 507 b. 



A single microspheric specimen at St. WS 505, rare at the other stations, where both 

 megalospheric and microspheric specimens were found, very finely developed, the 

 spines sometimes attaining considerable length. All the stations are in the far south of 

 the Bellingshausen Sea, depths 572-1500 m. This is a Pacific species, but was recorded 

 by the 'Terra Nova' from the Ross Sea. 



