38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



The cardinalia of the brachial valves of the two genera are very 

 similar and a median septum or ridge is lacking from both of them. 

 The crura of both genera are of the same falcifer type and the outer 

 hinge plates are developed to about the same degree. 



Assigned species. — At present two species only are assigned to this 

 genus : 



Rhynchonella salpinx Dall. 

 R. holmesii Dall. 



Distribution. — Eocene (Castle Hayne), North Carolina. 



Discussion. — Tertiary brachiopods are a rarity in the United States 

 and that is especially true of the genus Probolarina. The two species 

 of this genus are represented by a few specimens only. They are 

 also quite different in form but the beak characters and the cardinalia 

 of the two appear to be identical. It is interesting that the cardinalia 

 of Probolarina are so like those of Rhytirhynchia, a modern inhabit- 

 ant of the Indian Ocean and represented in the fossil state in Okinawa. 



PROBOLARINA HOLMESII (Dall) 



Plate 17, B 



Rhynchonella holmesii Dall, Trans. Wagner Free Inst. Sci., vol. 3, pt. 6, p. 1536, 

 pi. 58, figs. 10, 12 (not 11), 1903. 



In Dall's description of this species it is stated that one of the 

 figured specimens is a young individual. The other specimen figured 

 is somewhat fragmentary, probably belonging to a different and 

 undescribed species. I here select the smaller of the two specimens 

 as the type of R. holmesii, U.S.N.M. 109298a. This specimen is 

 clearly a young form of those figured on plate 17, B. Specimen 

 U.S.N.M. 549359 is a well-preserved adult of R. holmesii. 



STREPTARIA Cooper, new genus 



(Gr. streptos, twisted) 



Plate 19, B, C 



Pentagonal in outline with the greatest thickness near midvalve; 

 valves unequal in depth, the brachial valve having the greater depth ; 

 anterior commissure uniplicate to twisted, either right or left; sur- 

 face marked only by concentric lines of growth, occasionally with 

 obscure marginal costae. Beak short, deltidial plates conjunct, 

 foramen hypothyrid to submesothyrid, small and usually with promi- 

 nent elevated rim. 



