134 THE NAIADES OF MISSOURI 



Cyprogenia Aberti (Conrad.) 



("Young Fan-Tail.") 

 PL XXV, Figs. 83 A and B. 



1850 — Unio aberti Conrad, Pr. Ac. Nat. vSci. Phila., V, p. 10; 1854, 



Jl. Ac. Nat. vSci. Phila., p. 295, pi. XXV, fig. I. 

 1885— ;7nzo popenoi Call, Bull, Washb. Col., I, p. 49, pi. II. 

 1900b — -Cyprogenia aberti (Conrad) Simpson, Proc. U. vS. Nat. Mus., 



XXII, p. 610. 



ANIMAL CHARACTERS. 



Nutritive Structures: — Branchial opening with many 

 short papillae; anal with finely crenulated inner edge; supra- 

 anal separated from anal by short mantle connection; mantle 

 edge antero-ventrad to branchial opening .slightly crenulate; 

 gills short, wide, inner wider than outer, inner laminae free from 

 visceral mass, except for a short distance anteriorly; palpi very 

 small, connected about one-half of their distance antero-dorsad; 

 color of soft parts dirty white, except for the black, squarish mott- 

 lings of the mantle edges arotmd the supra-anal opening. 



Reproductive Structures: — Marsupium formed by five 

 to seven ovisacs originating from the edge of the outer gills antero- 

 ventrad and extremely elongated posteriorily into a coil; conglu- 

 tinates white, very long, solid, club-shaped; glochidia unkown. 



SHELL characters. 



External vStructurEs: — Shell sub-triangular, compressed; 

 beaks rather pointed, sculpturing obscure; post umbonal ridge 

 prominent with a hummocky expansion middle-ways for the 

 female shell, not so sculptured in male; radial furrow rounded 

 moderately wide; dorsal ridge faintly ribbed; disk entirely 

 rugose; epidermis brownish yellow with numerous banded ra3^s 

 marked with mosaics of green mottlings of various patterns of 

 geometric designs. 



Internal Structures: — Cardinals double in each valve; 

 laterals double in left, single in right; interdentum long; beak 

 cavities deep; nacre bluish, irridescent. 



Sex Length Height Diameter Locality 



cf 42 X 32 X 16.5 (St. Franci.s R., Greenville 



9 40 X 32 X 16.0 (White R.. HoUister) 



cf 37 X 30 X 14.5 ( " 



V 30 X 22 X II. o ( '■ ■ ' ; 



