BRAOcHIOPODA. 879 
Subgenus Rhaetina, Waagen. 1882. 
Shells biplicate ; loop short, supported by crural plates ; dental 
plates absent. 
Fias. 548-551. Rhaetina gregaria, Suess (sp.). (ZUGMAYER.) 
(Type, Rhaetina gregaria, Suess (sp.). Triassic.) 
Subgenus Dictyothyris, Douvillé. 1880. 
Shells subnaviculate, with median fold and sinus on brachial 
and pedicle-valves respectively. Surface covered with short 
spinules. Dental plates are present in the pedicle-valve. In the 
Fies. 552-555, Dictyothyris coarctata, Parkinson (sp.). (Davipson ) 
brachial valve is a well-developed cardinal process and faint 
median septum ; the loop is short, its anterior band being broad 
and considerably reflected. 
(Type, Dictyothyris coarctata, Parkinson (sp.). Jurassic.) 
Magellania, Bayle. 1880. 
Synonym; Waldheimia, King. 1850; Weothyris, Douvillé. 1880. 
Shells biconvex, ovate or subpentagonal. Surface plicate or 
smooth, Beak of the pedicle valve broadly truncated, Deltidial 
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