342 THE AMERICAN MIDLAND NATURALIST 
1900b—Lampsilis ellipsiformis Simpson, Proc. U. S. Nat. Mus., XXII, 
Pp. 557- 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening with numerous 
yellowish papillae; anal very finely papillose; supra-anal small, 
high, closely but distinctly connected to anal; gills large, pointed 
even in the marsupial ones; inner laminae of inner gills connected 
entirely to visceral mass; palpi sickle-shaped; color of soft parts 
the usual dirty white with posterior mantle edges blackened. 
REPRODUCTIVE STRUCTURES:—Marsupium occupying posterior 
half of outer gills, consisting of about twenty ovisacs separated by 
thick septa, when gravid extending below the original edge of sterile 
marsupium, tips pigmented with bluish, beaded spots; mantle 
edge antero-ventrad to branchial opening with papillae terminating 
in rather fine crenulations centrad-ventrad; conglutinates and 
glochidia unknown. 
EXTERNAL STRUCTURES:—Shell small, elliptical, dorsal and 
ventral lines about the same curviture; post-umbonal ridge rather 
rounded; beaks very low, usually eroded, even in the youngest 
shells, thus sculpture not seen; epidermis brownish-yellow with 
bright waved rays all over disk; no sculpturing on disk; shells 
somewhat sexually dimorphic, the female being rather swollen 
post-ventrad. 
INTERNAL STRUCTURES.—Cardinals strong, upright; inter- 
dentum large and thick; laterals short, stout, very slightly curved; 
beak cavities shallow; nacre white, sometimes with slight pinkish 
tinge and teeth rusty-red. 
Sex Length Height Diameter Locality 
Stee Ome Bava Exe 2oeoihintd (Gasconade R., Gascondy) 
oh A Te Bey ey en Gh on tersrioboal (Osage R., Warsaw) 
OY ne Set Wane Gnea ey oatieal (ae poe ee LOeCton) 
OTS 5 eek 2) OX 7.5mm (Niangua R., Hahatonka) 
MISCELLANEOUS REMARKS:—This little striped shell is common 
throughout Central Missouri, but is never found anywhere in the 
interior north of the Missouri River and is rare in the southern 
drainage. Its shell may sometimes be taken for young N. liga- 
mentina; however, the adult shells of these species are nothing alike. 
The anatomy of both are very similar; however, the inner mantle 
edge antero-ventrad to branchial opening is more specialized and 
indicates a step in advance. Hundreds of females were examined 
