scHccHERT] BKACHIOPOD TERMINOLOGY. 77 



Umbonal slopes. — Tlic inclined surl'aces about the umho and ojjposite 

 the cardinal slojies, 



W'litral valre. — The valve situated on the ventral sidf of the animal, 

 and Laving in youth or maturity a delthyrium or pedicle opening- 

 through which the pedicle is protruded, except in Iphidea, Obolella, 

 Lingula, etc., where the pedicle protrudes between the valves. AVheu 

 the shell is cemented to foreign bodies it is always by the ventral 

 valve. It is usually the larger and deeper of the two valves. Pedicle, 

 large)., dental, neural, aud receiving valves are synonymous terms. 



