BRACHIOPODA. 



Shell punctate ; spheroidal ; beaked ; hinge line shorter than 

 the width of the shell ; cardinal extremities rounded. Internal 

 spires as in Spirifera. Ventral valve with a flattened space or 

 false area beneath the beak, on each side of which, at the base, 

 is a strong tooth ; a narrow medio-longitudinal septum extends 

 from the beak to the base. Dorsal valve furnished with a strong 

 spatulate cardinal process, which, rising vertically from the 

 cardinal margin, is closely grasped at its base by the cardinal 

 teeth of the other valve ; and thence bending abruptly upwards, 

 and expanding, is projected into the cavity of the opposite beak, 

 lying close upon the under side of the false area. Cardinal pro- 

 cess grooved to allow of the passage of the peduncle, for the 

 protrusion of which a minute foramen is sometimes observed rn 

 the beak. The crural processes originate at the base of the 

 cardinal process. A medio-longitudinal septum as in the ventral 

 valve. 



Surface of shell apparently smooth, under a lens punctate ; 

 when perfect, covered with minute hair-like spines. 



The larger species of this genus present some analogy in 

 external appearance with Spirigera, and the presence of internal 

 spires increases the similarity. The cardinal teeth resemble those 

 of Spirigera and Merista. In form, and in the punctated test, it 

 simulates Magas ; while the elongate cardinal process of the 

 dorsal valve resembles that structure in Thecidium. 



Distribution, 7 species. Silurian. United States, England 



Trematosrera, Hall, 1859. 



Etymology, trema, a foramen, and spira. 



Example, T. multistriata, Hall. 



Shell transverse, elliptical, or subrhomboidal, furnished with 

 internal spires (arranged as in Spirifera) ; hinge line shorter 

 than the width of the shell. Valves articulated by teeth and 

 sockets ; beak of ventral valve produced or incurved and trun- 

 cated by a small round perforation separated from the hinge 

 line by a deltidium. A deep triangular pit or foramen beneath 

 the beak, which is filled by the closely incurved beak of the dorsal 

 valve. False area sometimes defined. 



Distribution, 7 species. Upper Silurian — Middle Devonian. 

 United States. 



This genus and the next appear to be closely related to 

 Jletzia. 



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