1898-1902. No. 32.] FOSSIL FAUNAS FROM SERIES B. 23 



other 6 mm. The outline is oblong subpentagonal, moderately globose. 

 The depression of the sinus is only marked in the anterior third of the 

 shell; it is characterized by having, with three broadly rounded plications, 

 a flat or slightly convex base. The fold, that is also conspicuous only near 

 the front, shows when seen from the front a corresponding, sub-rectangular 

 section with in one specimen four, in the other only two rounded plica- 

 tions. One of the plications of the latter specimen shows, however, a 

 division into two quite near the margin. The furrow in the middle of the 

 fold is visible across the whole valve, from the front to the beak. On the 

 lateral portions 3 4 distinctly marked plications, in a very good light 

 we find an indication of still others near the beak. In one of the speci- 

 mens particularly the plications show a tendency to divide into two. The 

 surface of the shell is marked by very fine concentric lines of growth. 



The chief characteristics of this form are the small size, the rect- 

 angular section of sinus and fold as seen from the front side and the 

 very broadly rounded plications with their tendency to divide. 



The form is related to Uncinulus nucleolatus HALL var. angulatus 

 MAYNARD from the Keyser of Maryland (see Low. Devonian p. 366, 

 pi. 64, figs. 1820) but differs by it small size and the characters of 

 sinus and fold. 



Occurrence: B, lower part, Seal Bay. 



Atrypidae. 



Atrypa DALM. 



Atrypa reticularis LINN. 



PL VIII, fig. 5. 



Very abundant from one locality, and showing as usual a good deal 

 of variation in form. The specimens are mostly relatively small, ranging 

 in width from 17 mm. down to 5 mm. The dorsal valve is usually not 

 very globose, the ventral varying from nearly flat to moderately con- 

 vex. The surface-ornamentation well marked without being extremely 

 strong. The younger specimens show a more evenly lenticular form and 

 fewer plications. 



Occurrence: B, upper part, over the fragment-limestone. Valley 

 south of Borgen. 



