344 THE PALEONTOLOGY OF MINNESOTA. 



LLingnlii riciniformis, var. galenensis. 



small size; second, a very sharply defined circular stage, which is of a lighter color 

 than the shell surrounding it. This second growth has been appropriately called 

 the Obolella stage, and around it the shell begins to assume its specific form, growing 

 most rapidly in the anterior region, and but comparatively little laterally and pos- 

 teriorly. At maturity, the apex is no longer marginal, as in the Obolella stage, but 

 has become submarginal through the addition of shell substance posterior to the 

 protegulum. These stages of growth indicate that the course of development of 

 Lingula is through Paterina Obolella Lingula. 



This species can be separated readily from Lingula attenuata Hall (non Sowerby) 

 =L. daphne Billings=L. (Glossina) trentonensis Conrad, sp., by its oval form and 

 obtuse beaks. The latter is also more attenuated towards the apex, and is now 

 referred to the sub-genus Glossina, Phillips. L. elongata Hall differs in being twice 

 the size of L. riciniformis. 



Formation and locality. Near the base of the Galena shales, associated with Zygospira recurvirostris 

 Hall. A single example has been discovered at Minneapolis, while from St. Anthony Hill, a suburb of 

 St. Paul, Minnesota, a number of specimens have been procured. Also in the Trenton at Middleville, 

 New York, and Charlesbourg, Canada. 



Collector. C. L. Herrick. 

 Mus. Reg. No. 785. 



LINGULA. KICINIPORMIS, var. GALENENSIS W. and 8. 



PLATE XXIX, FIGS. 10 and 1^. 

 1892, April 1. Lingula riciniformis, var. galenensis W. and S. American Geologist, vol. ix, p 284. 



The conspicuous differences between L. riciniformis Hall and this variety are 

 that the former is constantly two-thirds the size of the latter, and that the greatest 

 width is across the center of the length of the valves, while the variety is widest 

 in the anterior third. In the Galena horizon at Oshkosh, Wisconsin, this variety is 

 not rare, and attains twice the size of L. riciniformis Hall. 



Formation and locality. From the Galena shales of the north branch of the Zumbro river, at the 

 upper bridge, near Kenyon, and near Fountain, Minnesota. Also from the Galena horizon at Neenah and 

 Oshkosh, Wisconsin. 



Collectors. W. H. Scofleld and Charles Schuchert. 

 Mus. Reg. Nos. 7672, 7673. 



LINGULA MODESTA Ulrich. 



PLATE XXIX, FIG. 41. 



1889. Lingula modesta ULRICH. American Geologist, vol. iii, p. 382, flgs. 4-46. 



Original description: "Shell small, subovate, widest in the anterior half, the 

 width and length, respectively, in four representative cases, 3.5 to 5.2, 5.5 to 8, 7 to 

 10 and 7 to 11, the figures representing the dimensions in millimeters. Both valves 



