600 



HISTORY OF SYSTEMS. 



Second sub-Class. 



DiMYARIA, 



/Ist sub-Order: 



Order 1st. The lobes of Shell regular. 



the mantle more ori 2nd sub -Order : 



less vmited. Shell irregu- 



V lar. 



{1st sub- Order : 

 Shell regular. 

 2nd sub -Order: 

 Shell irregu- 



lar. 



TJiird sub-Class, j Order 1st : a foot. 

 MoNOMYARiA. (Order 2nd: no foot. 



BRACHTOPODA. 



* Valves articulated. 



Family 1. ProductidtE. No tendinous ligament. Pro- 

 ductus. 



2. Terebratulid^. a tendinous ligament. Te- 



rebratula. 



3. Thecideid^. Shell adlierent. Thecidea. 



** Valves free. 



4. LiNGULiD^. A long tendinous pedicle fixed to 



the beaks. Lingula. 



5. Orbiculid^. Pedicle short, by the middle of 



the lower valve. Orbicula. 



6. Craniad^. Shell adherent without ligament. 



Calceola, Crania. f 



DIMYARIA. 

 Order I. 



* Shell regular. 



7. TuBicoLiD^. 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, Plio- 

 ladomya, Solen, Panopaea. 

 10. MyarIjE. 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, 



