324 MOLLUSCOIDEA—BRACHIOPODA SUB-KINGDOM V 
branch supporting one process of the divided hinge-plate. Silurian ; North 
America and Europe. 
Camarotoechia, Hall and Clarke (Plethorhyncha, H. and C.) Rhynchonellae 
with the dorsal median septum bearing posteriorly an elongate cavity. 
Cardinal process absent; dental lamellae present. Ordovician to Carboni- 
ferous ; North America and Europe. 
Leiorhynchus, Hall. Like Camarotoechia, but with the plications on the 
lateral slopes usually faint or obsolete. Devonian to Carboniferous. 
Wilsonia, Kayser (Uncinulina, Bayle). Sub-cuboidal or sub-pentahedral 
Rhynchonellae with the low plications marked anteriorly by fine median lines. 
Dental lamellae present. No cardinal process. Silurian and Devonian ; 
North America and Europe. 
Uncinulus, Bayle. Like Wilsonia, but with the hinge-plate undivided, and 
with a well-developed cardinal process. Devonian; North America and Europe. 
Hypothyris, King. Sub-cuboidal Rhynchonellae with a very rudimentary 
dorsal median septum. Plications as in /Vilsonia. Vascular sinus frequently 
strongly impressed in the ventral valve. Devonian; North America and 
Europe. 
Pugnaz, Hall and Clarke. Rhynchonellae with a deep dorsal and shallow 
ventral valve, and very prominent fold and sinus; otherwise resembling 
Hypothyris. Devonian to Carboniferous ; North America and Europe. 
Eatonia, Hall.  Rhynchonellae with large, flabellate, deeply excavated 
muscular scars in the ventral valve. No dental lamellae. Cardinal process 
large, resting upon a short median septum, and bifureate at its summit. 
Devonian ; North America. 
Terebratuloidea, Waagen. Lhynchonellae with very large apical foramen, 
but without dental plates, cardinal process, or median septa. Carboniferous 
to Permian ; India. 
Rhynchopora, King (Rhynchoporina, Oehlert). Plicate Rhynchonellae with 
the shell substance punctate. Carboniferous to Permian ; Europe and North 
America. 
Rhynchonella, Fischer (as restricted by Hall and Clarke), (Fig. 543, 4). 
Sub-pyramidal shells with a prominent anterior linguiform extension. Dental 
lamellae and a dorsal median septum present. No cardinal process. Jurassic 
and Cretaceous. 
Upwards of 600 species of Rhynchonella have been described, most of which 
are found in Mesozoic strata (Figs. 543, B, 544). It is probable that but few of these 
agree with the type species, I. loxia, from the Upper Jura of Russia. Hall and Clarke 
have shown that many American Palaeozoic species belong to other genera ; and Bittner 
has also removed from Rhynchonella many Triassic species. It is probable that no 
Palaeozoic Rhynchonellae s.s. exist. 
Halorella, Bittner. Sharply plicated Rhynchonellae with a median sinus on 
both valves. Alpine Trias. 
Austriella, Bittner. Small triangular, usually smooth- shelled Rhynchonellae 
without prominent fold and sinus. Alpine Trias. 
Norella, Bittner. Like Austriella, but with prominent anterior fold and 
sinus. Alpine Trias. 
Rhynchonellina, Gemellaro. Transverse Rhynchonellae with fine radial 
striae. Cardinal margin nearly straight, with a low concave ventral area. 
