TETRADELLA [Beyrichia quadrilirata Hall and Whitfield 1875, 
p.105,pl.4,f.6,7] Ulrich 1890,p.112 [Beyrichiidae 
by Ulrich; Tetradellidae by Swartz 1936,p.551; 
Beyrichiidae-Tetradellinae by Kay 1940a,p.265; 
Hollinidae-Tetradellinae by Hessland 1948,p.98, 
99,340; Tetradellidae-Tetradellinae by Henningsmoen 
1953,pe213,266) Ordovician, Ohio. 
TETRADELLIDAE Swartz 1936,pe551, a family to include 
Dilobella, Tetradella, Ceratopsis, Kiesowia, 
Thomasatia, Bassleratia, Bellornatia, Raymondatia. 
TETRADELLIDAE of Henningsmoen 1953,pe197,212,266 includes 
the subfamilies Tetradellinae, Piretellinae, and 
Bassleratiinae. 
TETRADELLINAE Schmidt 1941,p.37 [= Tetradellidae Swartz 
1936,(part); t Beyrichiidae (part) + Piretellidae 
Opik 1937 (part) + Dilobellinae Kay 1940], a 
subfamily of Hollinidae for the genera: Tetradella, 
Tallinella, Ceratopsis, Kiesowia, Ri ideliay 
Ctenobolbina (Ctenobolbina) and more doubtfully: 
Dilobella, Pseudostrepula, Ctenobolbina (Duhmbergia), 
Polyceratella. 
TETRADELLINAE Henningsmoen 1953,p.266, a subfamily of Tetra- 
dellidae for the genera Tetradella, Dilobella, 
Tallinnella, Hesslandella, Ceratopsis, ?Polyceratella. 
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