46 PROCEEDINGS OF THE NATIONAL MUSEUM vol.87 



HEDERELLA CHESTERENSIS, new species 



Plate 6, Figures 9-11 



Zoarium incrusting brachiopods, cup corals, crinoid stems, and 

 other organic objects indiscriminately, where it forms colonies some- 

 times several square centimeters in area, particularly well distinguished 

 by the curved clusters of zooecia produced in the course of branchmg. 

 From the single-tubed primary branch a gently curved zooecium 

 emerges at about 45° and within a short distance by successive bud- 

 ding forms a cluster of 4 or 5 zooecia usually curving away from the 

 branch, then after a short interval a similar group arises on the other 

 side. Likewise, the secondary branches emit alternately such zooecial 

 groups. Zooecia are about 2)^ mm. long, 0.3 mm. wide, and average 

 3 in 5 mm. 



Occurrence. — Chester group: Marion (cotype), Sloans Valley (co- 

 type), near Stephensport, Smithland, etc., Ky. (Glen Dean limestone) ; 

 Evansville, Ind. (cotype) ; and Chester, 111. 



Cotyfes.—U.^.^M. Nos. 50316, 54112, 54095-54099, 54127, 

 87953. 



HEDERELLA ADNATA (Davis. 1885) 



Plate 11, Figures 10-12 



Nicholsonia adnata Davis, Kentucky Foss. Corals, pt. 2, pi. 78, fig. 19, 1885 (not 

 described) . 



This species, although resembling H. mgans in its general zooecial 

 arrangement, differs in that the tubes are wider (0.6 mm.) and more 

 robust in general, the zoarial branching, although irregular, occurs 

 usually at a distance of 5 mm., and the zooecial tubes are much longer 

 (2.5 mm.) and more closely set, with 2 in 5 mm. and an angle of bud- 

 ding of 30°. Although rather common, all the specimens of this 

 species have been found incrusting fenestellid bryozoans. 



Occurrence. — Onondaga (Upper Jeffersonville limestone-*S'^myer 

 acuminatus bed): Falls of the Ohio at Louisville, Ky. 



Plesiotyjpes.—V.S.^.M. No. 54085. 



HEDERELLA 7 LAXA (Whiteaves, 1891) 



Plate 13, Figure 1 



Stomatopora laxa Whiteaves, Contr. Can. Pal., vol. 1, p. 210, pi. 28, figs. 8, 8a, 

 1891. 



The generic position of this species is still doubtful, although it is 

 perhaps best placed with Hederella. A gutta-percha squeeze of the 

 type seems to indicate that the zooecia bud from the middle of the 

 side of the preceding tube as in that genus. The branches divide at 

 intervals of 3.5 mm. and at an angle of less than 45°, and the zooecia 

 are unusually short and broad (1.2 mm. long and 0.65 mm. wide), 



