Second sub-Class. 



DlMYARIA. 



600 HISTORY OF SYSTEMS. 



ilst sub-Order: 

 Shell regular. 

 2nd sub -Order : 

 Shell irregu- 

 lar. 



11st sub- Order : 

 Shell regular. 

 2nd sub -Order: 

 Shell irregu- 

 v lar. 



Third sub-Class. [Order 1st: afoot. 

 MONOMYARIA. { Order 2nd : no foot. 



BRACHIOPODA. 



* Valves articulated. 



Family 1. PRODUCTION. No tendinous ligament. Pro- 

 ductus. 



2. TEREBRATULIDN. A tendinous ligament. Te- 



rebratula. 



3. THECIDEIDN. Shell adherent. Thecidea. 



** Valves free. 



4. LINGULID^E. A long tendinous pedicle fixed to 



the beaks. Lingula. 



5. ORBICULIDN. Pedicle short, by the middle of 



the lower valve. Orbicula. 



6. CRANIAD^E. Shell adherent without ligament. 



Calceola, Crania, f 



DlMYARIA. 

 Order I. 



* Shell regular. 



7. TUBICOLIDN. 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, Panopaea. 

 10. MYARIN. 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. 



