684 THE PALEONTOLOGY OF MINNESOTA. 



" [Macronotella scofieldi. 



Macronotella scofieldi, n. sp. 



PLATE XLIII, PIGS. 30-34. 



Size.— rig. 30. Length 1.57 mm.; hight 1.05 mm.; thickness 0.78 mm. 

 Fig. 33. Length 2.20 mm.; hight 1.33 mm.; thiclsness 1.05 mm. 



Valves varying in length, semiovate or nearly semicircular, the dorsal outline 

 not quite straight, being somewhat prominent centrally; free edges with a sharply 

 impressed furrow, forming a beveled border; surface strongly convex, rather full in 

 the centre-dorsal region, and marked, except on the ends and along the ventral 

 border, by rather large and somewhat distant pits; a row of these pits, more closely 

 arranged than usual, encircles a smooth subcentral spot. 



Of the two specimens figured, the smaller is from Minnesota, the other from 

 Kentucky. The latter, it will be observed, is not only larger, but also proportionally 

 longer at the hinge line. The smooth spot, furthermore, is less centrally situated. 

 I attach no importance to these differences, believing that they are quite within the 

 ordinary limits of local, if not individual variation. 



Named for Mr. W. H. Scofleld, of Cannon Falls, Minnesota, to whom not only 

 the author, but the Geological Survey of the state as a whole, is indebted for much 

 valuable assistance. He has been particularly active in the development of the 

 paleontology and stratigraphy of the Lower Silurian rocks of the state. 



Formation and locality. — Lower Trenton limestone, near Cannon Falls, Minnesota; Birdseye lime- 

 stone, High Bridge, Kentucljy. 



Family CYTHEEELLID^. 

 Genus CYTHERELLA, Jones and Bosquet. 



Cytherella Jones, 1848, Subgenus of Cythere; Monog. Entom. Cret. Form., p. 28; Bosquet, 1852, as 



a distinct genus; Desc. Entom. Foss. Terr. Tert., p. 10. 

 Jones and Kiekby, 1867. 

 Jones, Kiekby and Brady, 1884. Monog. Carb. Etom., Pal. Soc. p. 70. 



Carapace oblong or ovate, compressed, especially in front; smooth or pitted; 

 valves thick and unequal, the right being much the larger and having its edge 

 grooved or rabbeted all round on the inner side for the reception of the edge of the 

 left valve; muscle-spot indicated by a roundish depression near the center of the 

 valve externally, and by a corresponding thickening within. Length 0.5 — 1.4 mm. 



Type: Cytherella ovata Rcemer sp. 



This genus was founded upon Cretaceous, Tertiary and recent species, but no 

 less than twenty Carboniferous forms, chiefly European, have been described as 

 congeneric with the type by Jones, Kirkby, Brady and Ulrich. So far as their 

 affinities may be determined from the carapace alone, the greater part if not all of 



