260 Systematic Paleontology 



Family ASCODICTYONIDAE 



Genus ASCODICTYON Nicholson and Etheridge, Jr. 



ASCODICTYON SILURIENSE Vine 



Plate XLVI, Fig. 2 



Ascodictyon stellatum var. siluriense Vine, 1882, Quart. Jour. Geol. See. 



London, voL xxxviii, p. 52, figs. 1, 2. 

 Ascodictyon stellatum var. siluriense Vine, 1884, Ann. & Mag. Nat. Hist., ser. 



V, vol. xiv, p. 81. 

 Ascodictyon stellatum var. siluriense Vine, Proc. Yorkshire Geol. and Polyt. 



Soc, vol. ix, p. 184, pi. xii, flg. 6. 

 Ascodictyon siluriense Vine, Proc. Yorkshire Geol. and Polyt. Soc, vol. xii, 



p. 88, pi. ii, fig. 1. 

 Ascodictyon siluriense Ulrich and Bassler, 1904, Smith. Misc. Coll., Quart. 



Issue, vol. xlv, p. 286, pi. Ixviii, figs. 11, 12. 



Description. — Vesicles pyriform, small end more or less drawn out, 

 0.1 mm. to 0.2 mm. in diameter, and 0.3 mm. to 0.5 mm. in length, ar- 

 ranged in clusters of four to eight, with groups of four or five occurring 

 oftener than six to eight. Connecting threads about 0.03 mm. in thick- 

 ness, comparatively straight, with clusters of vesicles occurring at in- 

 tervals of 2.5 mm. or more. 



The Maryland specimen identified with this widespread Silurian 

 species agrees in all essential details with the above description. The 

 preservation of this specimen, however, is not of the best and it is possible 

 that more material may show differences of varietal if not specific im- 

 portance. 



The only known specimen from this horizon is incrusting a brachiopod. 



Occurrence. — Helderbetig Formation, Keyser Member. Cash Valley. 



Collection. — U. S. National Museum. 



Order CYCLOSTOMATA 



Family CERAMOPORIDAE 



Genus CERAMOPORA Hall 



Ceiuvmopoea ? incondita n. sp. 

 Plate XLI, Figs. 13-17; Plate XLIV, Figs. 1-3 

 Description. — Zoarium beginning as a crust on foreign bodies which it 

 may cover entirely or spread beyond, often growing by superposition of 



