CLASS II 



BRACHIOPODA 



379 



Eleutlierocrania von Huene. Biconvex Craniids related to Petrocrania. 

 Ordovician ; Esthonia. 



A B V 



Fig. 558. 



Craniscus velatus (Quenst. ). 

 Upper Jura; Oerlinger 

 Thal, Würteniberg. Interior 

 of ventral valve, Vi (after 

 Quenstedt). 



Fig. 559. 



Ancistr<}crania parisiensis (Defr.). Upper Cretaceous ; France. 

 A, Prottle of dorsal valve. B, Interior of same. C, Interior of ven- 

 tral valve, i/j. 



Craniscus Dali (Fig. 558). Ventral interior divided by septa into three 

 cavities. Jurassic ; Europe. 



Ancistrocrania Dali (Fig. 559). Dorsal valve with two muscular fulcra. 



Fig. 560. 



Isocrania igfiabergensis (Retzius). Uppermost Cretaceous ; Ignaberga, Scania. A, Profile and dorsal aspect 

 of Shell, i/j. B, C, Interior of ventral valve. D, Interior of dorsal valve, enlarged. 



Cretaceous ; Europe. Isocrania Jaekel (Fig. 560). Exterior plicate. 

 Cretaceous ; Europe. 



Fholidops Hall (Craniops Hall). Biconvex and but slightly attached 

 Craniids. Ordovician to Carboniferous ; North America, England, Gotland. 



Fseudocrania M'Coy (Palaeocrania Quenstedt). Radially striated shells 

 much lik'e Fholidops. Ordovician ; Europe. 



Cardinocrania Waagen. Permian of India. 



Order 3. PROTRBMATA Beecher. 



Specialised (through atrematous Kutorginacea), articulate, calcareous 

 Brachiopoda, with well-developed cardinal areas. Exterior surface nearly 

 always either plicate, striate or spinous, and but rarely smooth. Pedicle 

 aperture restricted to the ventral valve throughout life and more or less 

 closed by a deltidium ; in some forms the pedicle is functional only in early 

 life and later the animals cement the ventral valve to foreign bodies. Chilidium, 

 spondylium and cruralium often present. Brachia unsupported by a calcareous 

 skeleton other than short crura. 



Superfamily 1. ORTHACEA Walcott and Schuchert. 



Progressive Frotreinata. The older gener a have immature spondylia that are 

 rarely freely suspended but are conimonly cemented directly to the valves ( = pseudo- 

 spondylia). In the great majority of the later gener a all traces of spondylia are lost. 



