BRYOZOA. 541 



directions from the base from 5 to 7 cm. Strong root-like 

 appendages spring from the free margins and from both fa 

 of the basal portion. Branches rigid, except near the base, 

 where frequent bifurcations make them appear flexuous. They 

 are also slender, from 0.3 to 0.4 mm. wide, with twenty to 

 twenty-one in 1 cm., but being well knit together the whole 

 frond appears comparatively strong. On the obverse the keel 

 is pronounced but never sharp, and bears, on an average, three 

 small nodes to the fenestrule. Zooecia in two ranges. Apertures 

 small, sub-oval or slit-like, seemingly situated in a groove at 

 the base of the keel, with the outer margin prominent, some- 

 times appearing almost spine-like; twenty-one in 5 mm., two or 

 three in each fenestrule. Certain saucer shaped depressions 

 which occasionally take the place of one of the zooecia, may be 

 of the nature of ooecia. Dissepiments half or less than half as 

 wide as the branches, scarcely depressed, carinate. Fenestrules 

 (beyond the basal parts) regular, elliptical or sub-quadrate, 

 fourteen or fifteen in 1 cm. On the reverse near the outer mar- 

 gin, the branches are straight, and covered with granose longi- 

 tudinal striae; the dissepiments half as strong, and the fenes- 

 trules sub-quadrate, with the length nearly twice the width. 

 Toward the base the branches and dissepiments, the latter par- 

 ticularly, are much thickened, so that the fenestrules gradually 

 become round -oval. The granules are also larger and no longer 

 arranged in longitudinal lines. 



This fine species may be compared with F. compressa and 

 F. serratula. The former differs in having much larger fenes- 

 trules and in wanting granules on the reverse. The latter in 

 being more delicate and smaller in every feature. 



Position and locality: Keokuk group. Bentonsport and 

 Keokuk, Iowa, and King's Mountain, Ky. 



FENESTELLA TRISERIALIS Ulrich. 



PI. L, figs. 4. 4a. 



Zoarium a foliaceous expansion. Branches rigid, of moderate 

 strength, 0.4 to 0.45 mm. wide, seventeen or eighteen in 1 cm.; 

 rather flat on the poriferous side, which alone has been seen. 



