OSTRACODA. 689) 
Bythocypris? curta.] 
BytHocypris (?) CURTA, ”. sp. 
PLATE XLIV, FIGS. 36—38. 
S1zE.—Length 1.03 mm.; hight 0.75 mm.; thickness 0.48 mm. A larger specimen has a length of 
about 1.5 mm. 
This is an unusually short, subovate form, the ends being nearly equal and, with 
the dorsal margin, forming an almost regular elliptic curve; ventral outline straight 
centrally; surface smooth; valves moderately and uniformly convex, one larger and 
strongly overlapping the other above, below and at one end. The end having no 
overlap is slightly narrower than the other. 
The subequality of the ends, especially as regards thickness, makes it difficult 
if not impossible to determine with certainty which is the right and which the 
left valve. Asa Bythocypris the larger of the two must be on the left side, and if this is © 
correct for the species, then the blunter of the two ends would be the anterior. In 
Macrocypris, a genus containing mostly elongate species, the right valve overlaps, but 
the carapace in the present species is too short for that genus. Of known species B. 
ovata Jones and Holl, a Wenlock form originally described as a variety of Cytherellina 
siliqua,* may be nearest, but differs like all other species of Bythocypris in being 
longer. 
Formation and locality.—Middle third (Rhinidictya bed) of the Trenton shales, St. Paul, Minnesota. 
BYTHOCYPRIS GRANTI, 7. sp. 
PLATE XLIV, FIGS. 39—42. 
SizzE.—Length 1.40 mm.; hight 0.68 mm.; thickness 0.7 mm. 
Length 1.17 mm.; hight 0.57 mm.; thickness 0.6 mm. 
Valves strongly convex, especially so ventrally, somewhat elongate elliptical in 
outline, the ventral margin convex but not so much as the dorsal, the ends sub- 
equally rounded but with the posterior one a little blunter than the anterior; surface 
smooth. 
This species is readily distinguished from B. cylindrica Hall, by its more equal 
ends and convex basal outline. It seems to be closely related to B. concinna Jones, 
of the Wenlock shales of England, but the outline is a little different and the valves 
thicker in the ventral part. The left valves of Krausella inwqualis and K. arcuata 
are somewhat similar yet not enough so to render confusion between them at all 
likely. 
The species is named for the promising geologist, Dr. Ulysses 8. Grant, of the 
Geological Survey of Minnesota. 
Formation and locality.—Middle third (Rhinidictya bed) of the Trenton shales, St. Paul and Minne- 
apolis, Minnesota. 
*Ann. Mag. Nat. Hist., ser. 4, vol. iii, pl. xtv, fig. 4; 1869, 
—44 
