326 MOLLUSCOIDEA—BRACHIOPODA SUB-KINGDOM V 
(SECTION A.) TEREBRATULA. 
Terebratulacea with the loops unsupported by a median dorsal septum at any stage 
of growth. Brachial cirri directed outwards in larval stages. 
Family 1. Centronellidae. Hall and Clarke. 
Terebratulas with the loops developing direct and composed of two descending 
lamellae, uniting in the median line and forming a broad arched plate. Devonian 
to Triassic. 
This family comprises the simplest of all Terebratuloids, and from it are probably 
descended the other loop-bearing families. 
Centronella, Billings (Fig. 547). Commonly small, smooth, plano-convex, 
or concayo-convex shells, with the descending branches of the loop broadening 
rapidly anteriorly, and uniting in a triangular, mesially ridged plate. 
Devonian ; North America. 
Rensselaeria, Hall. Ovate or elongate-ovate striate Terebratuloids. The 
descending branches of the loop diverging for a short distance, thence acutely 
bent, converging, and uniting in an elongate triangular plate, which on the 
posterior margin gives off a small, pos- 
teriorly directed, rod-like process. Hinge- 
plate large and often much thickened. 
Thick dental plates present. Lower 
Devonian ; North America and Germany. 
Beachia, Hall and Clarke. Lentiform 
finely striated ensselaeriae with the 
lateral margins of the valves inflected, 
the anterior plate of the brachidium 
Centronelia glans-fagen, Hall. Devonian; Erie Droader, and the rod-like process longer. 
eto Bade B, Protile and dorsal aspect, 1/1. Tower Devonian ; North America. 
err Newberria, Hall (Rensselandia, Hall). 
Resembling Rensselaeria externally, but without the striate surface. Interior 
strongly marked by muscular scars and vascular sinuses. Devonian ; North 
America and Europe. 
Oriskania, Hall and Clarke. Large Centronellae with a continuous hinge- 
plate bearing a thin vertical spur or cardinal process. Lower Devonian ; 
North America. 
Selenella, Hall and Clarke. Biconvex Terebratuliform shells with a 
Centronella-like loop, but the triangular plate not mesially thickened. De- 
vonian ; North America. 
Romingerina, Hall and Clarke. Small biconvex Centronellae with the 
median ridge on the anterior plate of the loop elevated into a high vertical 
lamella almost touching the ventral valve and extended both anteriorly 
and posteriorly. Devonian to Lower Carboniferous ; North America. 
Trigeria (Bayle), Hall and Clarke.  Plicated, plano-convex Centronellae. 
Devonian ; France, Brazil, and North America. 
? Scaphiocoelia, Whitfield. Very large, plicate, plano- or concavo-convex, 
Centronella-like shells exteriorly. Loop unknown. Shell substance fibrous, 
impunctate. (?) Devonian ; South America. 

Fic. 547. 
