BRYOZOA. 181 
Stictoporella.] 
Between the ends of succeeding zocecial apertures one or two small mesopores. 
There is usually a row of these small pores along the border of the branches. Inter- 
spaces narrowly rounded or ridge-shaped, comparatively thin.” 
This neat species is near S. interstincta from the Utica horizon of the Hudson 
River group, but has somewhat narrower branches, fewer mesopores, and much thin- 
ner walls. In S. angularis the walls are much thicker, branches wider, sloping areas 
about the zocecial apertures polygonal, and the mesopores less numerous and irregu- 
larly distributed. S. dumosa has wider and oftener divided branches. 
Formation and locality.—Rare in the lower part of the upper third of the Trenton shales, at St. Paul, 
Cannon Falls, and near Fountain, Minnesota. 
STICTOPORELLA DUMOSA 7. Sp. 
(Not figured.) 
Zoarium forming bushy masses, as much as 100 mm. in diameter and 50 mm. 
high, consisting of very irregularly divided, free or coalescing, small branches, 1.5 to 
2.0 mm. in width, and usually less than 0.5 mm. in thickness. Zocecial apertures 
subcircular or elliptical, set into rather wide sloping areas of polygonal or rounded 
outline, the shape depending upon the number of mesopores present. Arrangement 
rather irregular; occasionally longitudinal rows, with the mesopores between the 
ends of the zocecial apertures, prevail, in which case the surface appearance is much 
the same asin S. rigida. More commonly, however, a diagonal arrangement predom- 
inates, with the mesopores distributed more at random. In these, especially when 
the mesopores happen to be fewer than usual, the general appearance is much more 
like that of S. angularis. Where the arrangement is the most regular there are ten 
or eleven zocecial apertures in 8 mm. diagonally, and about eight in the same space 
longitudinally. Apertures often closed by a slightly convex plate, in which a minute 
subcentral perforation may be detected. Walls ridge-shaped, generally wider than 
the diameter of the zocecial apertures. Mesopores varying in number; sometimes a 
fragment will show about one only to each zocecium, while others may have them 
three or four times as numerous. Edges sharp, generally exhibiting two or three 
rows of mesopores. 
Internal structure, especially in transverse and vertical sections, very similar to 
that of S. cribrosa. In tangential sections the mesopores are not as distinct, and the 
divisional line between the zocecia less sharply defined, than in similar sections of 
that species. 
Asa rule, I do not favor descriptions of species without illustrations, but in this 
~ ease the form is so easily recognized that the omission may be pardoned. Com- 
pared with S. angularis it is distinguished by its more irregular and stronger growth, 
