BRYOZOA. 539 



expansion at intervals of 4 to 8 mm.; number of branches in 

 1 cm., nine or ten; average width of same, about 0.7 mm., 

 just before bifurcating it is 0.8 or 0.9 mm. and just above the 

 division 0.5 or 0.6 mm. Dissepiments slender, less than half as 

 wide as the branches, rounded or sub-carinate, Fenestrules 

 large, of variable form, usually subangular and two or three 

 times longer than wide; about four or five in 1 cm. Carina 

 strong, rounded, bearing a row of small nodes about 0.8 mm. 

 apart. Zocecia in two alternating ranges, from seven to eleven 

 in the length of a fenestrule, and fourteen in 5 mm. Apertures 

 circular, about 0.16 mm. in diameter. In well preserved ex- 

 amples with a prominent peristome. In such the interspaces 

 and carina are finely striate. On the reverse the branches are 

 strongly convex and striated longitudinally. In tangential sec- 

 tions the solid substance on the sides of the branches is seen to 

 be traversed transversely by very fine and crowded tubuli. 



The very large size of the branches and fenestrules distinguish 

 the species from all known to me. Indeed its branches with 

 their two ranges of zocecia are fully as large as those of Fenes- 

 tralia sancti-ludovici Prout, in which there are four rows. 



Position and locality: Keokuk group. King's Mt. Tunnel, 

 Kentucky (On Gin. South. R. R.). 



FEXESTELrLA COMPRESSA UMch. 



PL L. Fig. 2a. 



Zoarium a flat foliar expansion, the largest fragment seen 

 being over 6 cm. long. It spreads unusually slow because of 

 the long intervals between the bifurcations. The branches, of 

 which there are fourteen or fifteen in 1 cm., are rigid (especially 

 on the obverse), and compressed laterally, so that the zooecial 

 apertures look side wise rather than upward. The width of the 

 branches is nearly uniform, varying but little from 0.35 mm. 

 On the obverse they are strongly keeled. The carina carries a 

 series of small nodes which are nearly or quite as numerous as 

 the zocecia on either side. Zocecia sixteen in 5 mm. four to each 

 fenestrule, with small apertures and faint peristome. Dissepi- 

 ments slender, sub-carinate, half as wide as the branches. Fenes- 

 trules sub-quadrate, appearing rectangular in specimens partially 



