BKACHIOPODA. 



339 



These shells are separated from Rhynchonella, because 

 the round hole is situated in the hinge margin, whilst 

 in that genus the hole is separated from that part. 

 D'Orbigny is inclined to divide this genus into two ; he 

 limits the above name to those shells which have neither 

 pores nor spines, and gives the name of Acanthothyris to 

 those which have perforated spines on the shell. 



The species are found in most formations, as well as 

 the oldest. This genus is considered by many synonymous 

 with Rhynchonella. 



Camerophoria. King, — • Shell hypothyriform ; coarsely 

 fibrous, and minutely punctured, with a small open fissure; 

 larger valve with the dental plate conjoined at the upper 

 margin forming an arch-shaped process, which is attached 

 by its crest to the (ventral) medio- longitudinal plate : 

 small valve with two long slender processes striking off 

 from the centre of the crural base — a horizontal plate — 

 and curving up towards the opposite valve ; also a spatula- 

 shaped process, originating a little below the latter, project- 

 ing considerably forward with an upward curve, and sup- 

 ported by the (dorsal) medio-longitudinal plate. 



The peculiar spoon-shaped supports distinguish this 

 genus ; formed from Terebratula Schlotheimi, &c. 



Uncites. Defrance. — Shell free (?), inequivalve, regu- 

 lar ; largest valve with a protruding beak, curved, not 

 pierced at the summit; that of the smaller valve is curved, 

 and concealed under that of the larger valve : hinge (doubt- 

 ful), from which hang two thin bony pieces, in the form of 

 scythes, which enter into the smaller valve ; a considerable 

 hollow is found both on the anterior and posterior side 

 — Fossil. 



A doubtful genus ; the species is U. gryphus. 



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