﻿352 STROPiriTUS 



ninj; parallel to the growth lines ; posterior ridoe full hut wide- 

 ly rounded ; surface with irre.^ular concentric sculpture ; epider- 

 mis varying from }ello\visii-o-reen to pale dirty olive, often 

 showing- a few feehle rays hehind, subshining; left valve with 

 a single feehle. somewhat stumpy, smooth tooth ; right valve 

 with one and sometimes a taint second pseudocardinal, which 

 are often slightly compressed ; muscle scars shallow ; nacre 

 dull, usually tinted with purple. 



Length 105. height 54, diam. ^^ mm. 



Type locality, Talladega Creek, .Mahania. Also, Shelby 

 County, Alabama. 

 Margaritaiia alabaiucnsis I,i:.\, Pr. Ac. X. Sci. T'hila., V, 1861, 



p. 41 ; Jl. Ac. N. Sci. Phila., \'. 1862, p. 104, pi. xvi, fig. 249; 



Obs., VIII, 1862, p. 108, pi. XVI, fig. 249.— Ci.ESSiN, Conch. 



Cab. Anc, 1876, p. 264, pi. lxxx, fig. 5. 

 Unio alabamcnsis Sowiir^^iiv, Conch. Icon., XVI, 1868, pi. 



Lxxxii. fig. 433. 

 Margaron (Margaritana) alahainensis Lea, Syn., 1870, p. 68. 

 St''of^hitiis coimasaiigacnsis, (part), vSimpson, Syn., 1900, p. 



618. 



I confess that this form and the MargaritaJia co>niasaitgaen- 

 sis and M. ges}teni Lea are quite j>uzzling. Unfortunately I 

 have been able to examine but little material belonging to the 

 group, and I am not at all sure but what all three are forms 

 of one and the same thing. The examples of gesnerii, which 

 I have seen, have rather strong, concentric sculpture. The 

 only certainly authentic coiiiiasaiigaoisis \ have seen is the 

 type, a young shell, which is narrow in front, has an unusually 

 high rounded posterior ridge and is dull greenish-yellow with 

 a few faint ravs behind. The type of alabamcnsis is subsolid, 

 and rhomboid, is subshining and has a pur])lish-tinted nacre 



Strophitus spillmanii (Lea). 



Shell elliptic rhomboid, sub.solid, inflated, inequilateral, with 

 full, high beaks and a full, but widely rounded, jiosterior ridge ; 

 beak sculpture a few very strong, concentric ridges ; anterior 



