390 C. E. Beecher — Revision of the Families of 



widens, the connecting bands and high septum recede, and finally 

 even these disapj^ear in Macandr evict and Magellania. 



The following table represents the genera arranged according to 

 the views expressed in this paper: 



Family 3'eeebkatulidje Gray. 



Loop free, developed by the growth and modification of two 

 primary lamellse. Cirri directed outwards in larval stages. 



Centkonellixje Waagen. 



Loop composed of two descending lamellae uniting in the median 

 line, forming a broad arched plate. 



Centronella Billings. Juvavella Bittner. 



HensselcBria Hall. Nualeatula ZuQ^maver. 



Neicherria Hall. 



Strixgocephalix^ Doll. 



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

 in front. Probably no median coiled arm. 



IStringoceplialus Def ranee. 



Terebratulixje DalL 



Loop usually short. Ascending branches, when present, formed 

 by partial resorption of a primary centronelliforrii loop. A median 

 unpaired coiled arm exists in recent genera. 



Crypt onella Hall. TerebratuUna d'Orbigny. 



Megalanteris Suess. Dictyothyris Douville. 



Dielasma King. Pygope Link. 



Dielasmina Waagen. Coenothyris Douville. 



Liothyrina (Ehlert. Glossothyris Douville. 



DiscoLTiNJE (=Discoliidie Fischer and CEhlert emend.) 



Loop short, continuous with the cirrated edge of the lophophore. 

 No coiled median arm. 



Discolia Fischer and (Ehlerl. ? Agulhasia King. 



Eucalalhis Fischer and CEhlert. 



