NO. 5 RHYNCHONELLOID BRACHIOPODS — COOPER 59 



features have not been seen in the other two genera. The deltidial 

 plates of Grammetaria are conjunct but those of the other two genera 

 are disjunct. However, those of Frieleia nearly meet. 



The interior of the brachial valve is the significant part of each 

 of these genera. In Frieleia the crural bases are attached to the 

 median septum but in addition a strong development of inner hinge 

 plates may create a small chamber at the apex. In Compsothyris the 

 crural bases are likewise supported by the median septum but no 

 comparable development of the inner hinge plates is known. In 

 Grammetaria the very young are similar to Compsothyris in having 

 the crural bases united to the median septum but the apical V-shaped 

 chamber thus formed is much broader and shallower than that of 

 Compsothyris. In the adult of Grammetaria the spaces between the 

 septum, shell wall, and the broad chamber are filled to form a thick 

 apical callosity between the crura. Thus the low septum ends in a 

 callosity at the rear of the adult shell. 



Assigned species. — At present only Hemithyris bartschi Dall is 

 known in this genus. 



Distribution. — Hemithyris bartschi is known only from Philippine 

 waters from depths of 161 and 298 fathoms. 



Discussion. — Only two specimens of this genus are known but they 

 indicate a brachiopod having several unusual characters. Although 

 the deltidial plates of the adult specimen are broken, probably in sepa- 

 rating the valves, those of the young specimen are quite definitely con- 

 junct even though broken slightly at their line of junction. This is 

 one feature that distinguishes this genus from Frieleia and Comp- 

 sothyris. Another feature of considerable interest is the development 

 of the brachial interior from a camerate brachial valve to one having 

 only a callosity at the posterior. The small camera of the young is 

 buried in callus as the valve grows and is completely obliterated. This 

 takes place to a lesser extent in Hispanirhynchia. The crura of 

 Grammetaria are more like those of Frieleia in not having prominent 

 outer hinge plates developed. In Compsothyris modest but definite 

 outer hinge plates are present, making the crura more suggestive of 

 Basiliola than of Frieleia. 



HISPANIRHYNCHIIDAE Cooper, new family 



Genus HISPANIRHYNCHIA Thomson, 1927 



Plates 10, 13, A, 21, G 



Hispanirhynchia Thomson, New Zealand Board Sci. Art, Manual 7, p. 159, 1927. 



Outline elongate triangular with the greatest width in the anterior 

 third; inequivalve, the pedicle valve being deeper than the brachial 



