34 MISSISSIPPIAN BRACHIOPODA 



somewhat in strength and usually situated about one-half millimeter 

 apart. The dimensions of the type specimen are : length, 12 mm. ; great- 

 est width, 8 mm. ; width at postero-lateral extremities, 6 mm. 



Remarks. The holotype only of this species has been observed, an illus- 

 tration of which is given on the accompanying plate. The specimen 

 is a single valve, whether pedicle or brachial cannot be determined, lying 

 upon a fragment of fine-grained, yellow sandstone. It is imperfect, being 

 somewhat broken upon the margins, but seems to be sufficiently distinct 

 from any of the other species recognized, and may be distinguished by its 

 ovate-subquadrangular outline. The specimens from the Waverly for- 

 mations of Ohio and Pennsylvania which have been identified with this 

 species by Winchell, Meek, and Herrick, are all specifically different 

 from this Iowa shell. 



Horizon. Chonopectus sandstone of the Kinderhook. 



LlNGULA LOUISIANENSIS n. sp. 



Pate I, Fig. 3 



Description. Shell small, much compressed, ovate-subquadrangular in 

 outline, the lateral margins gently convex in the central portion, postero- 

 laterally the curvature increases and passes into the somewhat narrowly 

 rounded posterior margin, antero-laterally the curvature increases more 

 abruptly than posteriorly, passing into the broadly rounded or sub- 

 truncate anterior margin. The dimensions of a nearly complete valve 

 are: length 9.7 mm., width 5.6 mm. 



Surface of the brachial ( ?) valve, in the internal cast, compressed along 

 the postero-lateral margins, the apex of the convex portion of the valve 

 Lying a little within the apex of the posterior margin, a slight median 

 ridge, indicated by a depression in the surface of the internal impression, 

 passes anteriorly from near the apex of the valve for nearly half its 

 length. 



Surface of the valve nearly smooth, marked by fine, but somewhat 

 irregular lines of growth, and by the faintest suggestion of radiating 

 striae. 



Remarks. The specimen from which the above description has been 

 made is a nearly complete internal cast of what seems to be a brachial 

 valve, with only fragments of the shell itself preserved. The external sur- 

 face is not well preserved anywhere, all that can be seen being restricted 

 to a few fragments of the shell still retained on the specimen. In size and 

 general form the species resembles L. gorbyi from the Chouteau lime- 

 stone, from which species it may be distinguished by reason of its sub- 

 truncate anterior margin. 



Horizon. Louisiana limestone of the Kinderhook. 



