BRAOHIOPODA. 



343 



Lingula riclniformis.l 



The figure of this species, as given by Billings, shows a strong median sinus, 

 which does not reach the anterior margin, but in the description, it is said that the 

 "shallow sinus extends all along the median line from near the apex to the front 

 margin," and that the latter is " straight or slightly sinuate " in the middle. Since 

 the example before us agrees with the original description, we do not hesitate 

 to identify this species as occurring in the Northwest. This example and the 

 one figured by professor Hall, like the Canadian specimens, are broken along the 

 cardinal line, and must have been "obtusely angular," as the earlier lines of growth 

 are semicircular t in outline, or Paten'wa-shaped, and not much crowded laterally. 

 The shell substance is thick, and composed of many corneous and calcareous layers, 

 with the surface glossy. 



Formation and locality. From the lower portion of the Hudson Eiver group, or Loraine shales, in a 

 small quarry on the north side of the Upper Iowa river, about two miles west of Granger, Minnesota. 

 Mr. E. O. Ulrich reports the species from the same horizon near Wykoff. The original specimens were 

 found in the Trenton limestone, at Montmorenci falls, and Island of Montreal, Canada, 



Collector. The specimen here figured was found by Mr. R. H. Hasse, and kindly donated by him to 

 the survey collection. 



Mug. Reg. No. 7671. 



LINGULA RIOINIFORMIS Hall. 



PLATE XXIX. FIG. 0. 



3847. Lingula riciniformis HALL. Paleontology of New York, vol. i, p. 95, pi. xxx, flgs. 2a, 26, 2c. 

 1892. Lingula (Glossina) riciniformis HALL. Ibidem, vol. viii, pt. i, pi. I, fig. 3. 



Original description. " Oval, convex, slightly attenuated towards the beak, which 

 is obtuse; surface nearly smooth, or with fine nearly obsolete concentric lines. 

 Fine radiating striae are sometimes visible; and the surface is sometimes slightly 

 ridged, as if from elevated lines beneath the outer lamina of the shell." 



'.--& 



FIG. 24. Stages of Lingula riciniformis. p. protegulum; o. obolella; s. nealogic. 



Our specimens of this species show three distinct stages of development; the 

 first shelled condition, or "protegulum,"* which is not distinct, owing to its very 



For a definition of this term, and description of the earlier stages of growth in Brachiopoda and their importance 

 in classification, see Dr. C. E. Beecher's valuable papers on " Development of the Brachiopoda," American Journal of 

 Science, April, 1892. 



