48 BRYOZOAN FAUNA OF THE ROCHESTER SHALE. 
Vertical sections are particularly instructive and bring out the generic characters. 
Diaphragms are wanting in the immature region of the zooecial tubes and few are found 
in the mature zone. Indeed, in a zoarium built up of several successive immature and 
mature regions the latter region is recognized chiefly by the presence of diaphragms. In 
the mesopores the diaphragms are at intervals varying from one-half to an entire diameter 
apart. The mesopores also exhibit a feature that has been noticed in other species of the 
genus, namely that at about the same height in the zoarium a number of mesopores with 
their close tabulation will cease as such and their places be taken by the untabulatcd 
zooecial tubes. The tabulation and size of the zooecia in this species are so different from 
those of other species of the genus that comparison is not necessary. Associated species 
with a similar zoarium are the various species of Monotrypa, but the absence of mesopores 
in these forms will easily distinguish them under a lens. 
This species i- named in honor of Mr. B. E. Walker, of Toronto, Canada, in appreciation 
of his keen interest in paleontology and his generous help in loaning many line specimens. 
Occurrence. Not uncommon at Grimsby, Ontario, and at Lockport and Rochester, N. Y. 
Catalogue number. 35527, U. S. National Museum. 
<>r<l<*i- CRYPTOSTOMATA \ in<*. 
Representatives of eighteen genera distributed among eight families of this order are 
found in the Rochester shale, making the Civptostomat a the best represented group, gen- 
erically at least. Cryptostomatous bryozoa are characterized by the primary zoceciJ 
orifice being produced into a tubular shaft — the vestibule. 
Family PHYLLOPORINIDJE UTrioli. 
Genus PHYLLOPORINA Ulrich. 
This genus comprises characters pertaining to several orders, and is one of the "compre- 
hensive" types that occur occasionally in Paleozoic strata. The zoarium is of irregularly 
anastomosing blanches, with two to eight rows of apertures on the obverse side, the reverse. 
longitudinally striated: tabulated interstitial spaces closed at the surface; acanthopores 
generally present. 
Phylloporina asperato-striata ( Hall). 
PL XV I II, figs. 1-5. 
Retepora asperato-striata Hall. Nat. Hist. New York, Pal. II. L852, p. 161, pi. 40C, figs. 2a-h. 
Subretrpora asperato striata Miller. North American Geol. and Pal., 1889, p. 326. 
Phylloporina asperato-striata Ulrich, Geol. Survey Illinois, VIII, 1890, p. 332, pi. 53, figs. 5-"5b 
J'l/i/lioporina asperato- striata Grahau, Bull. New York State Mus., No. 45, 1901, p. 168, fig. 68. 
Zoarium of rather regularly inosculating branches arising from a slightly expanded base 
and forming a reticulate. Hat, undulating or broadly funnel-shaped expansion, sometimes 
reaching a diameter of 70 or 80 mm. Branches varying from 0.8 to 1 mm. in width, but 
usually the different parts of the same specimen are uniform in this respect. Fenestrules 
rather regular in shape, oval to subelliptical, but somewhat variable in size, the average 
being about 1.10 mm. in length and 0.45 mm. in width. Measuring longitudinally 9 to 10 
fenestrules may be counted in 20 nun., while transversely 15 occupy the same space. The 
celluliferous side exhibits 4 to 6 ranges of zooecia. Apertures circular or subpolvgonal, 
closely crowded together, 6 to 7 in 2 mm. In well-preserved examples the longitudinal 
striae of the reverse side are seen under a magnifier to be minutely denticulate, thus sug- 
gesting the specific name. 
Both the external and internal characters of this well-marked species have been figured, 
the former by Hall and the latter by Ulrich. The large anastomosing branches with four 
to six rows of polygonal zooecia are readily recognized. 
Occurrence. — Abundant at Lockport, Rochester, Niagara Falls, and other localities where 
the Rochester shale outcrops in western New York, and at Grimsby, Thorold, and Hamilton, 
Ontario. Rare in the Osgood beds at Osgood, Ind. 
Catalogue number, 35740, 35741, 43441, U. S. National Museum. 
