Prof. T. Rupert Jones—Fossil Ostracoda from U. States. 387 
view is narrower. Some few individuals (figs. 6a, b, for instance) 
have a strong dorsal depression just behind the front hinge, and 
a deformation of the antero-ventral border. This furrow is irregular; 
but the largest example is figured here. Sometimes the depression 
consists of two narrow sub-triangular hollows. It is difficult to 
determine if this be a varietal character, or the result of accident or 
disease. 
The original Cypridea tuberculata (Sowerby) is sub-quadrate and 
relatively shorter and thicker than either var. adjuncta or the form 
under notice. The latter is sufficiently distinct to have a varietal 
name— Wyomingensis 
From the Bear-River Formation ; Cokeville, §..W. Wyoming. 
III. Poramocyrris, Brady, 1870. 
3. POTAMOCYPRIS AFFINIS, sp. noy. Pl. XV. Figs. 8a, 5. 
Length -7, height °4, thickness ‘22 mm. 
This is not far distant in shape from Cytherideis [?] Marshii, 
Jones; but it is more oblong, being less attenuate posteriorly, and 
has not so great a lateral convexity. 
Some of the fossil Ostracoda formerly referred to Cytherideis 
probably belong to Potamocypris; and I think that C. Marshii and 
the specimens now under notice should be regarded as belonging to 
this genus. I propose to name the present form as P. affinis. The 
species of this genus live in fresh and brackish waters. 
From the Bear-River Formation ; Cokeville, 8.-W. Wyoming. 
4, Poramocypris unisutcaTa, Jones. Pl. XV. Figs. 10a, 0. 
Length 1:05, height -65, thickness -45 mm. 
The “ Cytherideis” unisulcata, Jones, Monogr. Tert. Entom., Pal. 
Soc. 1856, p. 48, pl. iv. fig. 10, and Suppl. Monogr. 1889, p. 46, was 
regarded as a doubtful species; but (its proposed genus, Cytherideis, 
having been revised and limited by G. 8. Brady and A. M. Norman, 
1889) its right place is in Potamocypris. 'To this P. unisulcata the 
present species aptly coincides. Its transverse furrow is at first 
sight a differential characteristic; but we find so many genera 
having species impressed with a more or less distinct transverse 
furrow” that we cannot remove this form from Pontocypris on 
account of that feature. 
P. unisuleata occurs in the green shale of the:Osborn Series, Cliff 
End,’ Isle of Wight, with Candona Forbesii, Jones, also Paludina, 
Melanopsis, Melania, Lepidosteus and remains of Alligator. 
Fig. 10 is from the Montana Formation ; Coalville, Utah. 
1 Grou. Mac. 1886, p. 147, Pl. IV. Figs. 6a, 3, c. 
2 A more or less perfect furrow marks the valves in some species of Cypris, Limni- 
cythere, Cytheridea, Cythere, Cytheropteron, Bythocythere, Cytherella, Cypridina. 
In the foregoing the sulcus is often rare and always irregular; but it holds good, 
however, more definitely as a generic character in the Paleozoic Hntomis and 
Entomidella, although partially shown in some contemporary genera, especially 
Primitia. 
3 Mem. Geol. Surv., Isle of Wight, 2nd edit., by Reid and Strahan, 1889, p. 150. 
