Bekde.] Carboniferous Invertebrate*. 127 



LIMOPTERIA. 



Meek aud Worthen, Proc. Chic. Acad. Sci., I, p. 29, (1866). 



Limopteria longispina. Plate XVI, i\g 6. 



Gi rvillia longispina Cox, Geol. Rep. Ky., in, p. 568, pi. vin, f. 6, (1857). 

 Monopteria longispina Keyes, Geol. Surv. Mo., v, p. 114, pi. xliii, f. 1, 

 (1894). 



Shell elliptical-subquadrate in outline ; antero-dorsal margin 

 nearly straight to the anterior margin, which is nearly circular, 

 the curve rapidly decreasing again to the extremity of the shell, 

 where it is sharply curved, almost angular; the posterior mar- 

 gin is a deep U-shaped sinus between the acute point of the ear 

 and the extremity of the shell. Beak placed well forward ; shell 

 very oblique ; umbonal ridge very prominent, extending to the 

 extremity of the shell, greatest curve about one-third the distance 

 from the beak, which protrudes slightly beyond the hinge line. 

 Anterior portion of the shell quite convex. The deflection of 

 the margin anterior to the beak, forming the lunule, is very 

 sharp, almost angular, and extends backward some distance. 

 The internal muscular impressions very faint, as excellently 

 preserved casts show practically no traces of them. Spine acute, 

 about three-fourths the length of the shell. The posterior ear 

 is separated from the shell by a moderately well-defined depres- 

 sion, which falls directly from the umbonal ridge, which is very 

 prominent. Surface marked by concentric stria 1 of growth 

 which are nearly parallel to the outline of the shell. 



Range and distribution : Upper Coal Measures ; Kansas City, 

 Turner. Lawrence. 



Some specimens from Lawrence are extremely long when 

 measured from the tip of the ear to the anterior margin. The 

 great length of the ear, with the convexity of this portion of 

 the shell, are its principal features. 



