250 The Sarcodina 



Family 3. Euglyphidae. Assulina Ehrenberg (55, 83. 107; Fig. 5. 33 D; Corythton 

 Taranek (107); Cyhhoderia Schlumberger (83, 107; Fig. 5. 33, I, J); Euglypha Dujardm 

 (83 107; Fig. 5. 29, G-I); Nebela Leidy (68, 83. 107; Fig. 5. 34, F-H); Pareuglypha 

 Penard'(107' Fig- 5. 33, E, F); Paulinella Lauterborn (78, 107; Fig. 5. 33, G, H); 

 Placocista Leidy (53, 107; Fig. 5. 34, I. J); Quadrula Schulze (83, 107; Fig. 5. 33 K, L); 

 Sphenoderia Schlumberger (83, 107; Fig. 5. 34, C-E); Trinema Dujardin (36, 83, 107, 

 151; Fig. 5. 34, A, B). 



Order 5. Foraminiferida 



Two features are characteristic— myxopodia and a test surrounded 

 by cytoplasm. The majority of living species measure less than 10 milli- 

 meters and are thus relatively small as compared with some of the extinct 

 species. However, there are exceptions, such as Bathysiphon filiformis in 

 which the test reaches a length of 50 mm (82). Most species are found in 

 salt and brackish water, and the few reported from fresh water are rela- 

 tively simple types. A small group contains specialized pelagic forms. 

 More typically, however, the Foraminiferida are slowly creeping organ- 

 isms, or else are migratory when young but sessile as adults. Various 

 sessile species have been found attached to eel grass and seaweed. Attach- 

 ment to seaweed or other floating objects presumably would be a signifi- 

 cant factor in the distribution of such species. 



The Foraminiferida as a group are distributed throughout the oceans, 

 but there are characteristic local faunas restricted to particular areas. 

 Vertical distribution is influenced by the type of shell, since calcareous 

 tests go into solution at deeper levels. Geologically, Foraminiferida are 

 represented from Silurian to Recent time, although they vary in abun- 

 dance in different strata. The association of specific types with particular 

 deposits has been applied to the determination of geological correlation, 

 especially in drilling for oil. The most common type of modern deposit 

 is Globigerina-ooze, formed from tests of pelagic Globigerinidae and 

 Globorotaliidae at depths of 500-2500 fathoms. 



Pseudopodia and their activities. Myxopodia are typical of Foramini- 

 ferida These sticky pseudopodia form a meshwork when extended and 

 show streaming of protoplasm, as indicated by the movement of granules 

 which may reach a rate of 400-500ij. per minute in Iridia lucida (81). As 

 described in Elphidium {Polystornella) crispum (66), this circulation may 

 be noted even in small branches of the network, granules moving up and 

 down the pseudopodia and occasionally reversing directions. Granules 

 flowing in opposite directions are often seen on opposite sides of a single 

 pseudopodium. Length of the myxopodia may equal or may greatly ex- 

 ceed the diameter of the test. In some instances, an organism with a test 

 measuring about 1.0 mm may form a myxopodia! net covering an area 

 20-40 mm in diameter. Myxopodia may show considerable activity. In 

 Elphidium crispum they are sometimes withdrawn at "lightning speed"; 

 or they may be shot out "like little rockets" and then wave about in the 



