BRACHIOPODA. 353 



Lingulasniatldae.l 



rather than separate them under a new name. L. tenuigrnnulata McCoy* is another 

 closely related species, but it and L. canadensis have three flattened slopes, another 

 character not seen in the Minnesota material. 



Formation and locality. Lower portion of the Galena limestone, in the quarries at Mantorville 

 and near Hacler, Goodhue county, Minnesota. The type specimens are from the Hudson River group of 

 Anticosti. 



Collectors. W. H. Scofleld, E. O. Ulrich and C. Schuchert. 

 Mus. Reg. Nos. 7681, 7682. 



Family LINGULASMATID.E, n. fam. 

 Genus LINGULASMA, Ulrich. 



1889. Lingulasma, ULKICH. American Geologist, vol. iii, p. 383. 



1889. Lingulelasma, MILLER. North American Geol. and Pal., p. 350. 



1892. Lingulasma, HALL. Paleontology of New York, vol. viii, pt. i, pp. 24, 46. 



Shell subquadrate, linguliform, inequivalve ; the dorsal valve considerably 

 the deeper. Beaks apical, that of the ventral somewhat extended beyond the 

 dorsal; cardinal margins gently sloping to the sides. Surface with the concentric 

 striae raised at irregular intervals into points, these being arranged in radiating 

 lines. 



Interior of the ventral valve with a low concave or concavo-convex platform 

 occupying from less to more than one-half the length of the shell; the anterior wall 

 may or may not be profoundly excavated. The ventral area has been enclosed more 

 or less within the shell, making a distinct sheath or shelf, beneath which is the 

 umbonal scar. Platform occupied by the progressive anterior, external and middle 

 lateral scars. Transverse scars present underneath the platform at its antero- 

 lateral angles. Crescentic scars scarcely defined. 



The dorsal valve deep, with a high platform occupying the posterior third or 

 one-half of the valve, centrally produced into a short or very long septum. The 

 anterior walls of the platform are more or less excavated, deepest close to the sep- 

 tum; marked by vascular sinuses laterally directed. The crescent is more or less 

 strongly developed, with its center sharply pointed posteriorly. In front of it is the 

 umbonal scar, and in the type species there is anterior to the latter impression a 

 short, sharp, median septum. Platform occupied by the lateral, transmedian, central 

 and anterior muscular scars. Transverse scars situated at the base of the platform 

 at its antero-lateral angles. 



Type : Lingulasma schucherti Ulrich. 



Lingulasma and Lingulops are the only linguloid genera in which interior plat- 

 forms are developed, and in this remind one strongly of the same parts in the 



*9eo Davidson's British Silurian Hraehiopoda, p. :I7. pi. 11. llgs. 9-14. 



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