FAMILIES OF LOOP-BEARING DRACHIOPODA 307 



Stringocephai.in^ Dall. 



Loop long, following the margin of the dorsal valve, not 

 recurved in front. Probably no median coiled arm. 



Strinyocephalus Defrance. 



TEREBRATULINiE Dall. 



Loop usually short. Ascending branches, when present, 

 formed by partial resorption of a primary centronelliform loop. 

 A median unpaired coiled arm exists in recent genera. 



CryptonMa Hall. Terebratulina d'Orbigny. 



3Iegalanteris Suess. Dictyothyris Douville. 



I)ielasma King. Pygope Link. 



DieJasmina Waagen. Coenothyris Douville. 



Liothyrina Qilhlert. Glossothyris Douville. 



Dyscoliix^ (= Dyscoliidae Fischer and CEhlert emend.}. 



Loop short, continuous with the cirrated edge of the lopho- 

 phore. No coiled median arm. 



Dyscolia Fischer and CEhlert. ? Agulhasia King. 



Eucalathis Fischer and Qihlert. 



Family Terebratellid^ King emend. 



Loop in the higher genera composed of two primary and 

 two secondary lamellae, development indirect, passing through 

 a series of distinct metamorphoses while attached to a dorsal 

 septum. Cirri directed inwardly during larval stages, at 

 which time the structure is comparable to that of Gwynia 

 and Cwtella. 



Dallinin^, n. sub-fam. 



Loop composed of descending and ascending lamellse, pass- 

 ing in the highest genera through metamorphoses comparable 

 to the adult structure of Platidia, Ismenia, Milhlfeldtia, 



