14 BRYOZOAN FAUNA OF THE ROCHESTER SHALE. 
Family ASCODICTYONID^ TJlricla. 
Genus ASCODICTYON Nicholson and Etheridge, jr. 
Zoarium parasitic, consisting of ovate or pyriform vesicles, arranged in radial clusters or 
isolated, and connected with each other by very delicate, hollow threads. Walls of vesicles 
perforated by closely arranged, minute pores. Zocecia unknown. 
Ascodictyon siluriense Vine. 
PI. IV, figs. 6-8. 
Ascodictyon stellatum Vine, Quart. Jour. Geol. Soc. London, XXXVII, 1881, p. 618. 
Ascodictyon stellatum var. siluriense Vine, ibid., XXXVIII, 1882, p. 52, figs. 1, 2. 
Ascodictyon stellatum var. siluriense Vine, Ann. and Mag. Nat. Hist. (5), XIV. 1884, p. 81, fig. 7. 
Ascodictyon stellatum var. siluriense Vine, Proc. Yorkshire Geol. and Polytech. Soc., IX, 1887, p. 184, 
pi. 12. fig. 6. 
Ascodictyon siluriense Vine, ibid., XII, 1892, p. 88, pi. 2, fig. 1. 
Ascodictyon siluriense Ulrich and Bassler, Smithsonian Miscell. Coll. (Quart, issue), XLV, 1904, p. 286, 
pi. 68, figs. 11, 12. 
Description (Ulrich and Bassler). — Vesicles pyriform, the small end moro or less drawn out, 0.1 mm 
to 0.2 mm. in diameter, and 0.A mm. to 0.5 mm. in length, arranged in clusters of four to eight, with 
clusters of fouror five occurring oftener than six to eight. Connecting threads about 0.03mm. in thick- 
ness, comparatively straight, with clusters of vesicles occurring at intervals of 2.5 mm. or more. 
Compared with A . stellatum, this species is distinguished by its usually fewer and less closely arranged 
vesicles in each cluster, by the greater average Lengl h and more pyriform shape of the vesicles, and by 
the comparative rigidity <>f the connecting threads. 
Several well-preserved examples of this cosmopolitan Silurian species have been found in 
the Rochester shale at Lockport. The pyriform radially arranged vesicles and the delicate 
connect ing threads form a zoarium so different from all associated bryozoa that comparison 
is unnecessary. 
Occurrence. — Vine's types were found in the Wenlock shale, Buildwas beds, Shropshire, 
England. In America the species occurs in the Rochester shale at Lockport, N. Y., and in 
the Waldron shale at Waldron, Ind., and Newsom, Tcnn. 
Catalogue numbers, 43135, 43138, U. S. National Museum. 
Order CYCLOSTOMATA T^iisli. 
The simple tubular zooecia with thin, minutely porous walls, the absence of marsupia 
and appendicular organs and the presence of oceeia characterize this order. The Cyclosto- 
mata are fairly well represented in this formation, the majority of the species belonging to 
the Ceramoporidse and Fistuliporidse, two families which have only recently been referred 
to the order with certainty. 
Family DIASTOPORID^ Busk (emend. TJlrich). 
Genus STOMATOPORA Bronn. 
Zoarium adnate, branching dichotomously ; zocecia subtubular or subpyriform, arranged 
in a single linear series; aperture subterminal. 
Stomatopora elongata (Vine). 
Pi. IV, figs. 10-14. 
Stomatopora dissimilis var. elongata Vine, Quart. Jour. Geol. Soc. London, XXXVIII, 1882, p. 50. 
Stomutopora elongata Vine, Ann. and Mag. Nat. Hist. (5), XIV, 1884, p. 85, fig. IV, 2. 
Stomatopora parva Ringueberg, Bull. Buffalo Soc. Nat. Hist., V, 1886, p. 20, pi. 2, fig. 16. 
Original description (V Ine) .—Stomatopora dissimilis Vine var. a. elongata. Zoarium very irregular 
clustering. Zocecia elongated, with, at times, long stoloniferous processes whicn intermingle with th< 
cells. When colonial growth is distinct, arrangement of cells is linear and uniserial. Measured unde: 
favorable circumstances, about three ceus occupy the space of one line. 
Locality. — Buildwas beds (Wenlock shales), England. 
