64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



ERYMNARIIDAE Cooper, new family 



ERYMNARIA Cooper, new genus 



(Gr. erymnos, fenced) 



Plates 18, A, B, 19, A, 22, B 



Outline irregular triangular to rounded pentagonal, usually with the 

 greatest width at or anterior to the middle ; inequivalve, the brachial 

 valve having the greater depth ; anterior commissure irregular, twisted 

 or regularly uniplicate ; surface smooth or marked by concentric 

 growth lines and short, irregular costae occupying the anterior third or 

 half. Beak of pedicle valve short, deltidial plates conjunct, slightly 

 auriculate ; foramen small to moderately large, oval, hypothyrid. 



Pedicle valve with short dental plates defining a deep delthyrial 

 cavity; muscle field small, with small adductor scars surrounded by 

 subflabellate diductor scars. Vascula media short. 



Brachial valve with large, deep, corrugated sockets ; socket ridges 

 elevated and strong; outer hinge plate broad; crura of septifer type, 

 curved, supported by two long septa that extend along the valve floor 

 for about one-fifth the valve length. Vascula media thin, moderately 

 long. 



Type species. — Terebratula polymorpha Massalongo, Schizzo geog- 

 nostico sulla valle del Progno o Torrente D'lllasi, con un saggio sopra 

 la flora primordiale del M. Bolca, Verona, pp. 18, 19, 1850. 



The septifer type of crura are not well known but have been recog- 

 nized in the Jurassic. Rothpletz recognized two groups or Sippe hav- 

 ing septifer crura. One of these is the Inversa-Sippe in which the 

 species have a sulcate anterior commissure and are smooth or semi- 

 costate ; the other group is the Trigona- Sippe in which the shells are 

 rectimarginate to uniplicate and are wholly costate. 



Septocrurella of Wisniewska is a paucicostate genus having a sul- 

 cate anterior commissure and the septifer type of crura. Rhynchonella 

 delaxa Oppel, which is similar exteriorly to Septocrurella sanctaclarae 

 Wisniewska, also has the septifer type of crura. 



No Cretaceous rhynchonelloids having this structure are now known 

 to me, but the fact that septifer genera appear in the Jurassic and 

 Eocene indicate the strong likelihood that specimens with this structure 

 occur in the Cretaceous. It is interesting to note that the known 

 Eocene septifer genus is smooth pauciplicate but is uniplicate rather 

 than sulcate. 



Comparison. — The exterior form of two species of Erymnaria is 

 like that of Streptaria in having the strongly twisted anterior com- 



