600 



HISTORY OF SYSTEMS. 



BRACHIOPODA. 



Family 1 . 

 2. 



Production. 

 ductus. 



TeREBRATULIDyE 



rebratula. 



ThECIDEIDyE. 



* halves articulated. 

 No tendinous ligament. 



Pro- 



A tendinous ligament. Te- 



Thecidea. 



5. 

 6. 



Lingulid/e. 

 the beaks. 

 Orbiculid/e. 



Shell adherent. 

 ** Valves free. 

 A long tendinous pedicle fixed to 

 Lingula. 

 Pedicle short, by the middle of 

 the lower valve. Orbicula. 

 Craniate. Shell adherent without ligament. 

 Calceola, Crania. f 



DlMYARIA. 



Order I. 



*" Shell regular. 



7. Tubicolid/E. Shell incrusted in whole, in part, 



or free in a tube which is either free or 

 enclosed. Aspergillum, Clavagella, Fistularia. 



8. Pholadaria. Shell free or within a tube, 



without ligament ; with apophyses under the 

 beak. Septaria, Teredo, Teredina, Pholas. 



9. Solenacea. Shell gaping at the ends ; liga- 



ment external ; hinge simple or with one or 

 two hooked teeth. Solemya, Glycimera, Pho- 

 ladomya, Solen, Panopasa. 

 10. MyarI/E. Shell inequivalve ; ligament internal 



t Mr. J. E. Gray has recently published a very elaborate classification of 

 the Brachiopoda in the Ann. and Mag. N. Hist. Ser. 2. ii. 435. 



