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1265 



TERTIARY FAUNA OF FLORIDA 



Romer in 1857 used an unmodified African vernacular name, taken from 

 Adanson, for this genus, but, later, realizing that this was not authorized by 

 the rules of nomenclature, attempted to substitute for it the name Caryatis, 

 which had already been used in entomology. If it is decided that vernacular 

 names should be excluded (and why should we use one from a negro dialect 

 any more than from English or French?), it will be probably best to give a 

 Latin form to Romer's name, as has been done with many of Adanson's, and 

 call the group Pitaria. It may be divided as follows : 



Section Pitaria s. s. Type Venus timiens Gmelin. 



Shell subtrigonal or ovate, convex, solid, smooth or concentrically sulcate 

 or waved ; pallial sinus ample, deep, reaching the middle of the shell, moder- 

 ately ascending ; hinge with a well-developed anterior lateral, the posterior 

 cardinals often grooved; lunule not deeply impressed, bounded by an incised 

 line, escutcheon not limited or well defined; internal margins entire, smooth. 



This group includes the majority of the so-called Cythereas, which have a 

 subtrigonal solid shell, unpolished, with an inconspicuous periostracum and 

 concentric sculpture of lines, wrinkles, small waves or sulci, not raised into 

 lamellae or distally elevated. They are nearly all tropical and largely Oriental 

 shells. 



Section Hyphantosoma Dall, 1902. Type Cytherea carbasea Guppy, 

 1866. Oligocene of Jamaica. 



Surface with fine zigzag sculpture as in Textivenus of the Venerine series, 

 otherwise as in Pitaria. 



Section Tivelina Cossmann. Type Cytherea tellinaria Lamarck. 

 Eocene. 

 Shell pointed behind, with a Tellina-like twist to the valves, which are 

 concentrically striate; hinge as in Chionella; pallial sinus short, bluntly 

 rounded. 



Subgenus HYSTEROCONCHA Fischer. 



Shell subtrigonal, plump, concentrically laminate ; lunule and escutcheon 

 situated in an impressed area and defined by a deeply incised line ; laminae 

 spinose near the boundary of the posterior area ; coloration tinted, not in pat- 

 terns ; inner margins smooth ; pallial sinus linguiform, ample, free, slighth' 

 ascending ; hinge as in Pitaria, the edges of the nymphs finely granular, and 

 the stout middle cardinal sometimes obscurely channelled. Habitat tropical 

 American seas. Type Venus dione Linne. 



