Loop-hearing JBrachiopoda. S91 



Family Teeebratellid^ 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 inwardh?- during larval stages, at which time the structure 

 is comparable to that of Gwynia and Cistella. 



Dallinin^, n. sub-fam. 



Loop composed of descending and ascending lamellae, passing in 

 the highest genera through metamorphoses comparable to the adult 

 structure of Platidia, Isrnenia, Muhlfeldtia, Terehratalia, and Dal- 

 lina. The lower genera, therefore, do not progress to the final 

 stages. 



Macandrevia King. Laqiieiis Dall. 



Dallina Beecher. Muhlfeldtia Bayle. 



JEudesia King. Kingena Davidson. 



Terehratalia Beecher. Ismenia King. 



Trigonosemns Koenig. Platidia Costa. 



Lyra Cumberland. 



Magellaniinje, n. sub-fam. 



Loop composed of descending and ascending branches, passing 

 in the higher genera through metamorphoses comparable to the 

 adult structure of Louchardla, Mag as, Magasella, Terebratella, and 

 Magellania. The lower genera become adult before reaching the 

 terminal stages. 



Magellania, Ba^de. Megerlina Deslongchamps. 



Terebratella d'Orbigny. Bouchardia Davidson. 



Magasella Dall. Kraiissina Davidson. 

 Mag as Sowerby. 



Megathyrinje Dall. 



Loop composed of descending branches only, passing in the 

 highest genus through stages correlative with Gioynia, Cistella, 

 and Megathyris. The lower genera do not complete the series. 



Megathyris d'Orbignj^ Zellania Moore. 



Cistella Gray. Gioyiiia King. 



Yale Museum, New Haven, Conn., March 15th, 1893. 



