THE NAIADES OF MISSOURI 1 79 



pium when gravid into blunt, pigmeted beads; mantle edge double 

 posteriorly, the inner one antero-ventrad to branchial opening 

 developed into a ribboned flap usually produced into a tentacled 

 lobe at its end located about the lowest post-ventral point; con- 

 glutinate not solid; glochidia rather large, subelliptic. 



Shell Characters: — Shell elliptical to ovate; disk smooth; 

 beaks sculptured by the sinuate or double-looped type, sometimes 

 with a tendency of the posterior loop to become broken; epidermis 

 usually smooth, thin and shiny often brillian^tly rayed. Hinge 

 with two cardinals and two laterals in left and two cardinals and 

 one lateral in the right valve; female shell with an inflation at 

 the post-ventral region of shell just over the marsupia. 



Miscellaneous Remarks : — The difl^rentiation of the mantle 

 antero-ventrad to branchial opening into a flap marks this genus 

 as among the highest of the Lampsilinae. This flap is so developed 

 with tentacles and papillae that it is often extended externally 

 and waved to and fro so as to produce almost the best possible 

 aeration for the embyros. This genus is represented in this State 

 by five species which have a good general distribution. 



Lampsilis anodontoides (Lea)/ 



("Yellow Sand Shell," "Lady's Finger.") 

 PI. VIII, Figs. 17 A and B; PI. XXVIII, Figs. 102 A—D. 



1834 — Unto anodontoides Lea, Tr. Am. PhiL Soc, IV, p. 81, pi. VIII, 



fig. II- 

 1834 — Unio teres Say, Am. Conch,. VI; 1820, Rafinesque, Monog. 

 1898 — Lampsilis anodontoides Baker, Moll Chicago, Pt. I, p. 100, 



pi. X, fig. I. 



animal characters. 



Nutritive Structures: — Branchial opening rather small 

 directed upward; anal crenulated; supra-anal high well separated 

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

 to visceral mass; palpi long, falcate, connected for one-half of 

 their length antero-dorsad; color of soft parts grayish except 

 brownish red mantle border at branchial opening. 



''■ From Rafinesque's evident description of this Species in the Suppli- 

 ment to his Monograph of 1820 under Umo teres {Elliptio teres) Lea's name, 

 as given here by Simpson, (1900b, p. 543,) should stand as a synonym for 

 Lampsilis teres (Raf.). 



