Thuranimina papillata Brady : a Study in Variation. 539 



In 1910 Cushman, in his work on the Foraminifera oC the 

 North Pacific Ocean (Ref. 38), records T. papillata and T. albicans 

 only, and criticizes adversely the rhizopodal origin of T. erinacea 

 Goes from that area (Ref. 27, p. 26). 



In 1913 we recorded (Ref. 39) two specimens from shallow- 

 water dredgings in the Clare Island District (Ireland), one being of 

 the normal T. 2'>apillata type, and the other a chitinous variety. 



In the same year J. A. Cushman described (Ref. 40) a new 

 species, T. papyracea, from "Albatross" Station D. 5613, North of 

 Celebes, 752 fms. It is defined as : " Test spherical, wall extremely 

 thin and delicate, composed of fine sand grains, sponge spicules, 

 and a brownish cement ; apertures very small and inconspicuous. 

 Diameter, 1 • 5 mm. A large species, with a paper-thin wall and 

 very inconspicuous apertures." 



Cushman's species is evidently only a pauperate modification of 

 the sphere type of T. papillata. 



In 1913 Dr. Ludwig Rhumbler, in one of the instalments 

 (Ref. 41) of his monumental work (as yet unfinished, and 

 perhaps doomed to remain incomplete, the death of the author 

 in the present war being reported), reproduces Brady's "Challenger " 

 figure as illustrating the formation of the secondary or outer 

 chamber by a flow of protoplasm from the papillae of the inner 

 shell, the protoplasm then proceeding to collect sand-grains for the 

 formation of an outer shell, as figured by Brady. He agrees with 

 the theory of Kemna (Ref. 34) as to this. He has not yet actually 

 recorded Thurammina from the material of the Plankton Expedi- 

 tion, and it does not appear in the undescribed plates which 

 appeared in Part I. of this work in 1909. 



In 1915 we recorded (Ref. 42) a single specimen from Kerimba, 

 Portuguese East Africa (6 fms.), characterized by the virtual 

 absence of papillaj, and another from 10-20 fms., presenting a transi- 

 tion form between T. papillata and T. albicans. 



In 1916 v/e recorded (Ref. 43) small individuals of the sphere 

 type, both arenaceous and chitinous, from Professor Herdman's 

 West of Scotland shallow- water dredgings. 



From the foregoing synopsis, which we believe contains at any 

 rate all the important references, it will be seen that the student of 

 T/iuram7nina is not confronted by such a bewildering medley of 

 species as encumbers other genera of the Foraminifera. Rejecting 

 T. erinacea Goes and T. splendens Egger as organisms of doubtful 

 identity, we are left with some nine specific divisions, or ten 

 including Thuramrninopsis canaliculata. But the examination of 

 several thousand specimens picked out from " Goldseeker " material 

 has convinced us that in Tkurammina we are dealing with a 

 protean and polymorphic type, and that it is more impossible even 

 than with other foramiuiferal genera to define the characteristics 

 and limitations of a species. Given a sufficient number of speci- 



2 2 



