﻿78 i,.\Mi>sii.is 



liii:,i;!nsii. Nevertheless the three forms are very jnizzling^ and 

 there are occasional specimens, which cannot be assigned with 

 much certainty to any of the three. 



Lampsh.is iiic.ginsu (Lea). 



Shell solid, inflated, gaping at the anterior base, oval, ellip- 

 tical or subquadrate with a feeble posterior ridge, with full, 

 high beaks placed well forward, whose sculpture consists of very 

 feeble, scarcch' loo]:)ed ridges, in front of which is a well-de- 

 veloped lunule ; ligament large ; surface with occasional irreg- 

 ular growth lines but generally smooth and somewhat shining ; 

 rest lines dark and usually well marked ; color, olive with occa- 

 sional faint rays ; left valve with tu'o triangular, short pseudo- 

 cardinals and two heavy laterals ; right valve with two. often 

 three pseudocardinals. the middle one the largest, and one 

 lateral, often having a vestige of another below it ; muscle scars 

 deep ; beak cavities moderate ; nacre silvery, flesh-color or sal- 

 mon-tinted. The male shell is bluntly pointed behind about 

 midwav uj) from the base ; the female is truncated behind and 

 has a very much-produced marsupial swelling at the extreme 

 posterior base. 



Length (male) 75. height 60. diam. 42 mm. 



Length ( female ) yo, height 60. diam. 40 mm. 



Ohio River, west to Iowa, and southwest to Kansas. 



Type locality, Muscatine. la. 

 Unio higginsii Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 84; JI. 



Ac. N. Sci. Phila., V, 1862. p. 188, pi. xxiv. fig. 258; Obs., 



IX, 1863, p. 10, pi. XXIV, fig. 258. — SowERBY, Conch. Icon., 



XVI, 1868, pi. i.xxxii, fig. 431. 

 Margaron (Unio) higginsii Lea, Syn.. 1870. p. 41. 

 Lampsilis higginsii Simpson, Syn.. 1900, p. 540. 



Var. grandis n. v. 



Shell higher and longer than the type, less inflated, that 

 of the female more produced at the posterior base, color pat- 

 tern generally more brownish, the umbonal region umlier- 

 colored. 



