FAMILY 15. SILICINIDAE 143 



Genus SILICINA Bornemann, 1874 



Plate 16, figure 16 



Genotype, by designation, Involutina polymorpha Terquem 



Silicma Bornemann, Zeitschr. deutsch. geol. Ges., vol. 26, 1874, p. 731. 



Test planispiral, either open or slightly divided ; wall arena- 

 ceous, usually siliceous and imperforate ; aperture formed by the 

 open end of the tubular chamber. 



Lias. 



Genus RZEHAKINA Cushman, 1927 



Plate 16, figure 1.5 

 Genoholotype, Silicina epigona Rzehak 



Rzehakina Cushman, Contr. Cushman Lab. Foram. Res., vol. 3, 1927, 



p. 31. 

 Silicina (part) RZEHAK (not Bornemann) , Annal. k. k. Naturhist. 



Hofmuseums, vol. 10, 1895, p. 214. 



Test planispiral, compressed, especially the central portion of 

 each side ; chambers forming a half coil ; wall thick, finely arena- 

 ceous, usually siliceous; aperture narrow, constricted. 



Upper Cretaceous and lowest Eocene. 



Genus INVOLUTINA Terquem, 1862 



Plate 16, figure 17 

 Genoholotype, involutina silicea Terquem 

 Involutina Terquem, Mem. Acad. Imp. Metz, vol. 42, 1862, p. 450. 



Test planispiral, or sometimes conical, the tubular chamber 

 partially divided by incomplete walls, sides of the test built up 

 with secondary additions; wall calcareous, arenaceous at least 

 on the surface; aperture circular at the end of the tubular 

 chamber. 



Jurassic. 



Genus PROBLEMATINA Bornemann, 1874 



Plate 16, figure 18 

 Genotype, by designation, Involutina deslongchampsi Terquem 



Prohlematina Bornemann, Zeitschr. deutsch. geol. Ges., vol. 26, 1874, 



p. 733. 

 Involutina (part) Terquem, Mem. Acad. Imp. Metz, vol. 44, 1863, p. 432. 



