BRACHIOPODA. 355 



Lingulusma galenensls.] 



On each side of these are large shallow depressions, the middle lateral (k) scars. 

 Transverse scars present at the base of the platform, at its antero-lateral angles. A 

 broadly rounded, slightly elevated, median septum has its origin underneath the 

 anterior end of the platform, and terminates at a point two-thirds the entire 

 length of the valve from the posterior margin. The inner surface of both valves 

 not occupied by the platform is marked by faint concentric undulations and radi- 

 ating striations; the latter are conspicuous on the lateral portions. 



Interior of dorsal valve with a concave platform occupying the posterior third, 

 more or less defined laterally, profoundly elevated, and excavated anteriorly. 

 Anterior edge of the platform produced in the center and supported by a short 

 septum, which terminates at about the center of the valve. Underneath the plat- 

 form, on each side of the septum, are well-defined vascular sinuses, laterally directed. 

 Near the apex of the posterior margin is situated a small crescent (cf), and in front 

 of it is a well-defined umbonal (g) scar, the anterior edge of which is strongly raised 

 above the platform. Sides of the platform occupied by the lateral (I) scars. On the 

 inner sides of the latter are situated the central (h) scars, leaving between them a 

 median triangular space. The anterior produced portion of the platform occupied 

 in part by the anterior (}') muscles. At the antero-lateral angles of the platform, 

 and indenting it, are situated the strongly defined transverse (t) scars. 



Length of the largest specimen, 35 mm.; width 28 mm.; thickness, 19 mm.; 

 another specimen measures respectively 27x22x14 mm. 



This species differs from L. sctiucherti Ulrich, the only other species of the genus, 

 in that the dorsal valve is deeper, platform and median septum shorter, and the 

 crescent smaller. In the ventral valve, the platform is also shorter and is of an 

 entirely different shape. The muscular scars of this species are likewise more dis- 

 tinct than in L. schucherti, while the interior ventral area is absent in L. galenensis. 



The posterior margin of the ventral valve in the two specimens of this species 

 is somewhat broken, but it is certain that this valve extended beyond the dorsal, 

 since the outline of the latter is distinctly visible. If an enclosed ventral area had 

 been developed in this species, such as is present in L. schucherti, there should be 

 evidence of it in these specimens. Since there is no proof of this nature, we are of 

 the opinion that the ventral area was mainly external in L. galenensis, and that 

 during the succeeding geological horizon, the Hudson River group, it receded more 

 and more internally. 



Formation and locality. Near the top of the Galena limestone on Bear creek, just south of Hamil- 

 ton, Fillmore county, and near the middle of this formation near Mantorville, Minnesota. Also in the 

 Galena limestone at Decorah, Iowa, and at Neenah and Oshkosh, Wisconsin. 



Collector. Charles Schuchert. 

 Mus. Reg. Nos. 768.'!-7686. 



