36 MISSISSIPPIAN BRACHIOPODA 



ing in its outline L. spatidata of the Genesee shale of the New York Devon- 

 ian. The species, however, is larger than the illustrated examples of L. 

 spatulata, and is more narrowly rounded at the anterior margin. 

 Horizon. Burlington limestone. . 



LINGULA VARSOVIENSIS Worthen 

 Plate I, Fig. 6 



1884. Lingula varsoviensis Worthen, Bull. No. 2, 111. State Mus. Nat. 



Hist., p. 24. 

 1890. Lingula varsoviensis Worthen, Geol. Surv. 111., vol. 8, p. 104, pi. 



11, fig. 8. 



Description. Shell rather large for the genus, subovate in outline, the 

 width about two-thirds the length, the greatest width anterior to the 

 middle. The dimensions of the holotype are: length 21.8 mm., greatest 

 width 14 mm. 



The valves moderately convex, the greatest depth posterior to the 

 middle; the anterior margin subsemicircular, the lateral margins gently 

 convex, the posterior margin shorter than the anterior, the postero- 

 lateral margins meeting at the beak in a broadly obtuse angle and round- 

 ing somewhat abruptly into the lateral margins distally, the beak ap- 

 parently not prominent. The surface marked by numerous, regular, 

 crowded, concentric lines of growth which are somewhat variable in 

 strength, becoming more crowded towards the margins ; the median one- 

 fourth of the valve is marked by faint, radiating costae which are only 

 noticeable anteriorly from the middle of the valve. 



Remarks. This species is one of the larger members of the genus in 

 the faunas under consideration, being equalled in this respect only by 

 L. indianensis. These two species are, indeed, closely allied and should 

 perhaps be considered as synonymous, but owing to the limited number 

 of specimens examined, the holotypes of the two species, it is not possible 

 to certainly determine their identity. The type of L. indianensis is rela- 

 tively a little broader, a character which may be due to the somewhat 

 crushed condition of the specimen, the concentric markings of the two 

 specimens are entirely similar in strength and expression, but the L. 

 indianensis does not possess the faint radiating costae in the median portion 

 of the valve which are present upon L. varsoviensis. For the present the 

 two species will be considered as distinct, their separation being based upon 

 the presence of the faint, radiating costae in L. varsoviensis and their ab- 

 sence in L. indianensis. More extensive collections may show that this 

 character is not of sufficient value to be used as a means of separating 

 the two forms specifically, in which case Worthen 's name L. varsoviensis 

 will be applicable to all of the specimens. 



Horizon. Warsaw beds. 



