SCAMMON : THE UNIONID.K OF KANSAS, PART I. 289 



Umbones rather flattened. Anterior and lateral slopes flat- 

 tened and rounded ; posterior slope very slightly excavated 

 and marked with two radial lines. Epidermis smooth and 

 generally shining, olive-brown. Ligament long and rather 

 thick. 



Interior : Pseudocardinals small, serrate, rather bluntly 

 pointed, single in the right and double in the left valve. 

 Laterals long, slightly curved, lamellar. Interdentum long, 

 narrow, rounded. Anterior adductor cicatrix well impressed, 

 large, much longer than wide ; posterior scars large, very 

 lightly impressed, confluent. Dorsal cicatrices on the lower 

 surface of the interdentum. Pallial line well impressed in its 

 anterior one-half and crenulate. Cavity of the beaks deep, 

 of the shell moderately deep. Nacre white, decidedly irides- 

 cent posteriorly. 



Dorsal pos- 

 Length. Height. Breadth. Um. ra. teriorangle. 



110 0.50 39 0.20 146° cT (432.1) 



L. pcnvellii is a southern form, found from Guadalupe river, 

 Texas, to the rivers of southern Kansas. It has been found 

 in Spring river at Baxter Springs (Call) , and a single male 

 specimen was among a lot of material received by the author 

 from Doctor Newlon and collected from the Neosho river at 

 Oswego. Call (5) mentions that his specimen bears broad 

 brownish rays over the dorsal slope. My specimen is too de- 

 corticated in this region to show this character, if present. 

 Lea states that the shell is eradiate. Poivellii can be distin- 

 guished from L. luteola, its nearest ally in local waters, by 

 the smaller and less pointed pseudocardinals and the thin- 

 ner, squarer and less inflated shell. 



Lampsilis ligamentina Lamarck. Plate LXV, fig. 2. 



Unio ligamentina Lamarck. An. sans Vert., VI, 1819, p. 72. 



Shell large, moderately thick — quite thick anteriorly — wide, 

 elliptical, slightly compressed. Anterior margin rounded ; 

 ventral margin more or less bowed ; posterior margin roundly 

 triangulate ; dorsal margin slightly curved. Umbones slightly 

 inflated and marked with from five to ten fine undulated ridges. 

 Anterior umboidal slope rather sharply rounded, umboidal 

 ridge prominent and obtusely angled. Epidermis marked 



