-236 THE FOEAMINIFEEA 



showing a prevalence of certain generic types best 

 fitted for those particular conditions. 



In the terrigenous deposits we find, for example, 

 the thin-shelled Foraminifera, as Lageiia, BoUviini, 

 Bidimina, and certain small forms of Gloh'ujerina 

 usually predominant, whilst porcellanous forms are 

 restricted to those which have a thin shell-wall, 

 or one constructed of fine arenaceous material. 



For an example of a terrigenous deposit of this 

 description we may quote a sample collected by the 

 U.S. Fish Commission steamer ' Albatross ' east of 

 Mariato Point, Gulf of Panama. This was a Green 

 Mud dredged from 695 fathoms. The chief forami- 

 niferal contents, enumerated by Dr. Axel Goes, are 

 as follows : Haj^lojjJiragnii/nii canariense, D'Orb. sp. ; 

 Textidayia .^agittula, Ya.i\ en neifoiiiii.s, D'Orb.; Boli- 

 Diua ]:)unda.ta^ D'Orb.; linVuituut ellipsoides, Costa; 

 Clieilostoinella ovoidea, Eeuss ; Lageiui luai-giiKifd, 

 W. and B. ; Nodo>iaria rapliniiini^ Linne sp. ; Uvigciina 

 pijgincea, D'Orb.; TJ. A/ibcriana, D'Orb.; Tniiica- 

 tidina Wueller.storfi, Schwager sp. ; T. mxiid/ila, 

 Brady, Parker, and Jones ; Botalia Soldanii, D'Orb. 

 sp. ; and a few pelagic species, as Glohigeriiia dithia, 

 Egger. 



The Greensands largely consist of green granules, 

 which on minute examination prove to be casts of 

 Foraminifera in Glauconite. In some samples of 

 Greensands the tests still remain, but more often 

 they speedily decay and only the cast is left. The 

 following is Dr. Brady's description of the note- 

 worthy ' Challenger ' sounding of Greensand off 



