682 THE PALEONTOLOGY OP MINNESOTA. 



[Moorea angularls. 



MOOREA ANGULARIS, n. Sp. 

 PLATE XLIII, FIG 89. PLATE XLVI, FIGS. 15-16. 



Size.— Length 0.67 mm.; hight 0.40 mm.; thickness 0.23 mm.; length of hinge line 0.65 mm. 



Valves compressed, suboblong, slightly leperditoid in outline, the posterior end 

 a little wider than the anterior; hinge line straight, nearly or quite as long as the 

 greatest length of the valve, with the dorsal angles acute; beneath them the outline 

 is nearly semicircular; ridge thin, almost marginal, strongest ventrally, wanting or 

 scarcely distinguishable dorsally; surface smooth, nearly flat. 



Two specimens only have been seen of this species. Both are figured, the one 

 from Minneapolis on plate xliii, the other, from Fountain, on plate xlvi. The latter 

 is the larger of the two and diflFers from the other, which is to be regarded as the 

 type, in several respects. Possibly it is distinct, but as it has evidently suffered from 

 weathering or maceration, the differences may not be normal, hence I perfer for the 

 present to classify it as an imperfect valve of M. angularis. 



The almost flat, though thick-edged valves of this species, cannot be mistaken, so 

 that comparisons are quite unnecessary. 



Formation and ZocaZi%.— Middle third (Rhinidictya bed) of the Trenton shales, Minneapolis, and 

 near Eountaln, Minnesota. 



MOOEEA PUNCTATA, n. Sp. 

 PLATE XLIII, FIGS. 84-88. 



Size.— Length 0.40 mm.; hight 0.24 mm.; thickness 0.18 mm. 

 Length 0.50 mm.; hight 0.32 mm.; thickness 0.22 mm. 



Valves somewhat oblong-quadrate, the hinge nearly straight, about one-flfth 

 shorter than the greatest length of the carapace; dorsal angles distinct; ends sub- 

 equal; not strongly rounded, sometimes obliquely truncate above; marginal, ridge 

 developed along the anterior, ventral and posterior borders, thinnest and least 

 prominent ventrally, thickest and somewhat club-shaped posteriorly, the ends 

 terminating abruptly before reaching the dorsal angles; ridge usually continuous, 

 but occasionally incomplete ventrally. Within the ridge the surface is flat and 

 minutely punctate; above it descends abruptly to the hinge line. 



A neat little species, reminding considerably of Placentula excavata Jones and 

 HoU, and of species of BoUia like B. vinei J. and H., or B. subcequata. It is smaller 

 than Moorea angularis, has less pronounced dorsal angles, a punctate surface, and 

 different marginal ridge. 



Formation and iocai%.— Upper third (Phylloporina bed) of the Trenton shales, St. Paul, Minnesota. 



