Braocwioro DA. 877 
disk, slightly bilobed in front and extending beyond the loop 
for one-third of its length. This disk is bordered by cirri. 
Fias. 534, 5385. Dyscolia Wyvillii, Davidson (sp.). (DAvIDSON.) 
Type, Dyscolia Wyvillii, Davidson (sp.). 
Distribution. Recent (West African and Caribbean provinces). 
Subgenus Glossothyris, Douvillé. 1880. 
Shells like Liorayrina but with a deep median sinus on the 
brachial valve. Loop short, anterior transverse band slightly 
recurved. 
Fias. 536-538. Glossothyris nucleata, Schlotheim (sp.). (QUENSTEDT.) 
(Type, Glossothyris nucleata, Schlotheim (sp.). Jurassic.) 
Pygope, Link. 1830. 
Synonyms ; Antinomia, Catullo, 1850; Pugztes, de Haan, 1833. 
Shells normally biconvex when young, but with increasing age 
the median growth of the valves is arrested, and by the continued 
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