684 THE PALEONTOLOGY OF MINNESOTA. 
{Macronotella scofieldi. 
MACRONOTELLA SCOFIELDI, 2. Sp. 
PLATE XLIII, FIGS. 30—34. 
SizE.—Fig. 30. Length 1.57 mm.; hight 1.05 mm.; thickness 0.78 mm. 
Fig. 33. Length 2.20 mm.; hight 1.33 mm.; thickness 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 centro-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 clos 
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 pe 
ordinary limits of local, if not individual variation. 
Named for Mr. W. H. Scofield, 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, Kentucky. 
Family CYTHERELLIDA. 
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 KirKsy, 1867. 
JONES, KirkBy 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 Roemer 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 
