FORAMINIFERA OF THK ATL.\NTIC OCEAN. 



79 



Description. — Test free or adherent, s])iral, trochoid, sjiirc varying 

 in its elevation, usually wider than high, chambers globose, all visi- 

 ble from above, only those of the last coil from below, sutures deeply 

 (k^pressed; test composed of from two to four volutions, the last- 

 formed one usu.'dly of 3-5 chambers, rapidly increasing in size as 

 added; wall of sand grains, the surface usually smooth; aperture an 

 arched slit on the ventral side of the chamber at its contact with 

 the adjacent cliamber of the previous volution; color reddisli l)rown, 

 occasionally gray. 



Diameter, 0.5-2 mm. 



Distribution.— This is a very ccnnmon and widely tlistril)uted 

 s})ecics in deep, cold waters. The records cover well the Atlantic 

 area where dredgings have been made. From the Albatross material 

 it is most common in the cold area off the northeastern coast of the 

 United States, but is found along the coast southward, in the Gulf 

 of Mexico, the Caribbean, and off the coa>.t of Soutli America. 



There is some variation in the height of the spire and in the relative 

 amount of cement used in the construction of the test and therefore 

 in its color. 



The species belongs to the genus Trocluimmina as here considered, 

 the difference in the height of the test being due to the globular 

 character of the cliambers. It is occasionally found attaclied and 

 the test surrounded, as is usual with other fixed species of the genus, 

 with an area of gray, finely granular particles. Such a fixed speci- 

 me)i is shown b}' Brady (pi. 35, fig. 11). 



Trncham mina gloh igcrin [for m is — n later ia I fxamined. 



