Beede.] Carboniferous Invertebrates. 125 



PTERIA. 



Pteria longa. Plate XVI, fig. 4. 



•vlllia longa Geinitz, Carb. u. Dyas in Neb., p. 32, pi. n, f, 15, (1866). 

 Amenta longa Meek, Fin. Rep. U. S. Geol. Surv. Neb., p 199, pi. ix, f. 8, 

 (1872); Meek and Worthen, Geol. Surv. 111., v, p. 578, pi. xxvi, f. 1, 

 (1873); etc. 



Meek's description : " Shell nearly or quite equivalve ; body 

 part obliquely elongated and more or less arcuate ; posterior 

 end narrow and abruptly rounded ; base yearly straight and 

 parallel to the cardinal margin behind, but ascending obliquely 

 forward from near the middle of the valves ; anterior side ob- 

 lique, and broadly and faintly sinuous under the ear. Hinge 

 line about three-fourths the length of the valves, and provided 

 with a marginal ridge, produced behind into a very narrow, 

 elongated ear, considerably shorter than the oblique portion of 

 the valves, from which it is separated by a deep sinus which 

 narrows to an abruptly rounded or subangular extremity close 

 under the ear ; anterior ear shorter and much broader than the 

 other, in the left valve convex, with its extremity pointed, and 

 faintly sinuous just below the point — separated from the swell 

 of the umbo by an oblique sulcus extending from the anterior 

 side of the same to the back part of the broad, shallow marginal 

 sinus of the ear. Beaks of both valves convex, very oblique, 

 placed one-fourth to one-fifth the length of the hinge back of 

 the anterior extremity ; in the right valve, rising a little above 

 the hinge, but in the left somewhat more prominent, according 

 to Professor (xeinitz's figures. Length of medium-sized speci- 

 men, measuring obliquely from the extremity of the anterior 

 ear to the posterior end of the body part of the valves, 9.61 

 inch ; height, measuring at right angles to the hinge, 9.33 inch ; 

 length of hinge, about 9.23 inch." 



Range and distribution : Upper Coal Measures ; Lawrence, 

 Topeka. 



