154 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



King, 1873 



1. Anterior laterals. 



2. Centrals. 



3. Umbonal. 



4. Transmedians. 

 5- Outside laterals. 

 6. Middle laterals. 



SCHUCHERT, 1897 



1. Retractors. 



2. Adductors. 



3. Pedicle. 



4. Rotators. 



5. Protractors (externals). 



6. Protractors (middles). 



7. Diductors. 



Block MANN, 1900 



1. Lateralis. 



2. Occlusor anterior. 



3. Occlusor posterior. 



4. Obliquus internus. 



5. Obliquus externus. 



6. Obliquus medius. 



DEFINITIONS 



Adductor Muscles. — (See Central muscles.) The term adductor 

 is used for the central muscles of the Protremata. 



Anterior Lateral (Retractor) Muscles. — In the Atremata 

 these extend from the outer lateral margins of the visceral area 

 in the ventral valve to its anterior extremity in the dorsal valve and 

 serve to readjust the dorsal shell. 



Anterior Region. — That portion of the shell in front of the 

 transverse axis and opposite the pedicle opening. 



Apex. — The place of initial shell growth. It may be the most 

 posterior portion of the valve or it may be situated near the trans- 

 verse axis. 



Apical Callosity. — The thickened boss at the inner side of the 

 apex of the ventral valve of Acrotrcta and other Neotrematous 

 genera through which the pedicle tube or foramen passes. 



Area. — See Cardinal area. 



Articulate Brachiopoda. — In the orders Protremata and Telo- 

 tremata the valves articulate by means of teeth and sockets. In 

 some Atremata rudimentary articulation is also developed. 



Atremata. — Primitive inarticulate, calcareo-phosphatic or cor- 

 neous brachiopods with the pedicle emerging more or less freely 

 between the two valves. (For a more detailed description see page 

 142.) 



Brachia. — The fleshy, coiled or spiral, ciliated appendages of 

 brachiopods serving in water circulation and respiration. 



BrachioccelE. — All of the anterior half of the valves outside of 

 the anterior portion of the parietal band. (After King.) 



