158 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



Pedicle Groove. — The median groove on the cardinal areas of the 

 valves formed by the pedicle extending through the posterior mar- 

 gin of the valves when they were closed. 



Pedicle Muscles. — In the Protremata and Telotremata one pair 

 originates on the ventral valve at points just outside and behind the 

 diductors, and another on the dorsal valve behind the posterior 

 centrals, while the opposite ends of both are attached to the pedicle. 

 Besides these, there is an unpaired muscle lying at the base of the 

 pedicle, attaching it closely to the ventral valve. 



Pedicle Opening. — See Delthyrium. 



Pedicle Tube. — See Foraminal tube. 



Platform. — An internal median thickening of the shell elevating 

 the muscles. Seen in certain families of the Atremata and more 

 rarely in the Neotremata. (See Spondylium.) 



PlEuroccELES. — Areas between the parietal band and the outer 

 postero-lateral margins. (After King.) 



Posterior Region. — That portion of the shell back of the trans- 

 verse axis and toward the beak, or apex. 



Protegulum. — The initial shell of brachiopoda. It is smooth and 

 of microscopic size, in outline being semicircular or arcuate and 

 without cardinal areas. Rarely seen in adult shells. 



Protractor Muscles. — See Outside and middle lateral muscles. 



Protremata. — Articulate, calcareous brachiopods, with the ped- 

 icle opening restricted to the ventral valve throughout life or during 

 early growth. Pedicle aperture modified by the deltidium. Brachia 

 unsupported by a calcareous skeleton, but nearly always by a more 

 or less long crura. ( For a more detailed description, see page 147. ■ 



Pseudo-area. — See Cardinal area. 



PsEudochilidium. — See Chilidium. 



PsEUDOCRURALiUM. — Dorsal -equivalent of pseudospondylium. 



Pseudodeltidium. — The convex medial portion continuous with 

 the ventral cardinal areas in Atremata and Neotremata. (See Del- 

 tidium.) 



Pseudo-pedicle Groove. — See Pedicle groove. 



Pseudospondylium. — See Spondylium. 



Retractor Muscles. — See Anterior lateral muscles. 



Septal Plates.' — Plates supporting the crural processes ; also 

 known as crural plates. 



Sessile Spondylium ^ Pseudospondylium. 



Spl.\nchnoC(T-;le. — The area within the parietal band. (After 

 King.) 



