OBOLID^. 521 



LiNGULELLA MOSIA OSCEOLA (Walcott). 



I' 



Plate XVIII, figures 2, 2a-c. 



Obolus (Lingulella) raosia osceola Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, p. 409. ((jnaraccenzed as below as a 

 new variety.) 



There is a considerable variation in the form of Lingulella mosia (Hall) as it occurs in the 

 brown sandstone of Osceola, and for the narrow, more elongate variety the name osceola 

 was proposed [Walcott, 1898b, p. 409]. It is an intermediate form between L. mosia and L. 

 perattenuata (Whitfield) (PI. XXI). The same, or a closely allied, variety occurs in a light-colored 

 sandstone at Eau Claire. 



The varietal name is derived from Osceola, the type locality. 



Formation and locality. — TTpper Cambrian: (78 and 78s) ^^ "St. Croix sandstone" in quarry near St. Croix River, 

 in suburbs of Osceola, Polk County, and (98) "St. Croix sandstone" near Eau Claire, Eau Claire County; botb in 

 Wisconsin. 



Lingulella nanno (Walcott). 



^^ Plate XXIV, figiu-es 1, la-d. 



Obolus (Lingulella) nanno Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, p. 409. (Described as below as a new 

 species.) 



Shell very small; general form elongate ovate, with the ventral valve subacuminate to 

 acuminate, and the dorsal valve elongate in outline. The convexity of the two valves is mod- 

 erate in the very small shells, increasing slightly with the increase in size. Average length of 

 the ventral valve is about 2 mm., and that of the dorsal valve a little less. 



The surface of the shell as it appears in the hard, fine grained, drab-colored limestone is 

 marked b}' fine, concentric striae, and very faint traces of radiating strife. 



Ohservations. — This minute species occurs in thin layers of limestone interbedded in the 

 Conasauga ("Coosa") shale. Its small size and acuminate ventral valve distinguish it from 

 other species. It is associated wdth Dicellomus appalacJiia Walcott and fragments of trilobites. 



Formation and locality. — Middle Cambrian: (16) Conasauga limestone, Blountsville Valley, Blount County; 

 and (91) Conasauga ("Coosa") sbale at Cedar Bluff, Cherokee County; both in Alabama. 



Lingulella nathorsti Linnarsson. 



Plate XXXI, figures 1, la-h. 



Lingulella ? nathorsti Linnarsson, 1876, Bihang till K. svensk. Vet.-Akad. Handl., Bd. 3, No. 12, pp. 1.5-16, PI. Ill, 

 figs. 24-30. (Described and discussed in English as a new species.) 



This is a medium-sized well-characterized species. As the illustrations of Linnarsson 

 [1876, PI. Ill] are not altogether satisfactory I have had several drawings made from material 

 received from Dr. G. Lindstrom. 



Plate XXXI, figures 1, la-b, represents specimens from the graj^, arenaceous, shaly sand- 

 stones at Andrarum, and Plate XXXI, figures Ic-e, specimens from the hard, dark-gray sand- 

 stones in Dalarne. Specimens from the dark sandstone show the surface of the sheU to have 

 been marked by concentric striae and lines of growth and very fine radiating striae. The casts 

 from the arenaceous shales show the area of the valves (PI. XXXI, figs. 1 and lb) and .traces of 

 the vascular markings. 



Ohservations. — In form and outline Lingulella nathorsti may be compared with L. radula 

 Matthew, but it differs greatly from that species in its surface characters. 



The specific name was given in honor of Mr. A. G. Nathorst. 



Formation and locality. — Lower Cambrian: (320x) In strata with Holmia hjerulfi at Andrarum, 20 miles (32 

 km.) northwest of Simrishamn, Province of Christianstad; and (8y) with Torellella cxvigata in the " Sparagmite " sandstone, 

 at Skarosen, northwest Dalarne, Province of Kopparberg; both in Sweden. 



' 178 is the type locality. 



