13 



has arrano-ed it. But it seems that he has confounded Stri- 

 gocephalus and Uncites of Defrance with Pentamerus, from 

 which they are really distinct, and placed Gypidia (to which 

 genus Goldfuss has referred Uncites Ch-j/phus of Defrance) 

 under Delthyris, along with Spirifer and Orthis. If the 

 principles of Von Buch's arrangement of the Brachiopods 

 are to be adopted, it will be necessary to place many of the 

 species of his genus Terebratula in the genus Delthyris, 

 and subdivide that genus into Strigocephalus, Pentame- 

 rus, Atrypa, Spirifer and Orthis. Calceola and Thecidea 

 would come well before Strigocephalus ; and Leptaena (in 

 the structure and use of whose tubular spines he has been 

 misled) will follow Orthis. So the section " Ohne Perfora- 

 tion "(without any perforation at the edge of the hinge) 

 will be found unnecessary, and Terebratula and Magas 

 will stand together ; this arrangement will be found very 

 natural. 



I would propose the following distribution of the order 

 Brachiopoda, as an improvement upon that of Von Buch. 



Brachiopoda. 



''Hinge none Lingula. 



Animal attaclied to fo- 

 reign bodies by the edge 

 of tlie shell through the 

 medium of a membranous 

 tube and ligamentous fi- 

 bres. 



With a hinge. Aperture 

 for the fibres of attachment 

 confined to the beak of the 

 larger valve. 



With a hinge. Aperture 

 for the fibres between the i 

 valves. 



Animal attached by 

 bres penetrating the disc 

 of one valve. 



Animal attached by th 

 surface of one valve 

 rectly. 



isc i-. 

 the! 



Tekebratula. 

 Magas. 



Calceola. 



Thecidea. 



Strigocephalus. 



Pentamerus. 



Atrypa. 



Spirifer. 



Orthis. 



Leptaena. 



.Orbicula. 



.Crania. 



