THE NAIADES OF MISSOURI ' 1 69 



Eurynia (Micromya) lienosa (Conrad.) 



("I^ittle Spectacle Case.") 



PI. XXVII, Figs. 96 A—D. 



1834 — Unto lienosus Conrad, An. Jl. Sci., XXV, p. 339, pi. i, fig. 4. 

 1900b — Lampsilis lienosus Simpson, Pr. U. S. Nat. Mus., XXII, p. 547, 

 1912b — Eurynia (Micromya) lienosa (Conrad) Ortmann, An. Car. 

 Mus., VIII, pp. 340 and 341. 



ANIMAL CHARACTERS. 



Nutritive Structures: — Branchial opening with two-ranks 

 of papillae; anal crenulated; supra-anal high, small, closely 

 connected by mantle edges to anal; inner laminae of inner gills 

 more or less free from the visceral mass ; palpi subf alcate connected 

 antero-dorsad about one-half of their length; color of soft parts 

 soiled white except mantle edge of siphonal area blackish, gills 

 brownish. 



Reproductive Structures: — Marsupium kidney-shaped, 

 restricted to posterior half of outer gill, consisting of twenty-five 

 distinct ovisacs, which, when gravid, distend transversely in middle 

 and ventrad as white beadlike bodies ; inner mantle edge of females 

 antero-ventrad to branchial opening with eight to ten conical 

 tentacles rather wide apart and reaching a little over half way 

 centrad- ventrad ; conglutinates large, club-shaped; glochidia large, 

 subovate, measuring 0.220 x o. 270 mm. 



SHELL CHARACTERS. 



External Structures: — Shell small, elliptical, moderately 

 inflated, thick; post-umbonal ridge rounded; disk smooth; umbones 

 low sculptured with inverted V-shapes; epidermis reddish brown 

 with dark banded rays; female shell expanded post-ventrad, male 

 rather biangulated behind. 



Internal Structures: — Cardinals double in left, single in 

 right valve; laterals also double in left, single in right; inter- 

 dentum lacking; beak cavities moderately deep; nacre purplish 

 with old gold and copper-color in branchial cavity. 



Sex Length Height Diameter Locality 



9 53 -^ 30 X 21.5mm (Black R., Williamsville) 



cf 50 X 30 X 2o.omm ( " " " ) 



o^ 42 X 26 X 17.0mm ( " " " ) 



9 29 X 18 X 1 1 .omm ( " " " ) 



