RHINOPORID^E. 6 1 
such a state of preservation or condition of growth that the interspaces have always 
appeared depressed and solid. From the manner in which the walls of the mesopores 
occupying the zooecial interspaces have been inserted, as shown on PI. XXII, their purpose 
seems to have been mainly that of a strengthening tissue. 
Altogether, both Lichenalia and Rhinopora are unique types of bryozoa and, so far as 
known, are restricted to Niagaran strata. Species described under these generic names 
from other horizons seem in all instances to belong elsewhere. 
Lichenalia concentrica Hall. 
PI. XXII, figs. 1-ii; PI. XXVI, figs. 7-10. 
Zichenalia concentrica Hall, Nat.. Hist. New York, Pal. II, 1852, p. 171, pi. 40E, figs. 5a-g. 
As this is the genotype and apparently the only valid species of the genus, the specific 
characters are as given in the generic diagnosis. The thin, unilaminate zoarium, large 
zooecia (averaging 0.5 mm. in their longer diameter), and the meandering surface canals, 
are characters making the species easily recognized. Good specimens can be found only 
in (he unweathered shales, and, in parting the shales, usually the epithecated side alone 
is shown. The disintegrated shales yield small fragments, but these, especially when 
still partly covered with clay, bring out the fact that the posterior portion of the zocecial 
wall is unusually high. On account of the unusual structure shown in this type, the 
species is figured in detail. 
Occurrence.— A characteristic fossil of the Rochester shale at Lockport, Rochester, and 
©ther localities in western New York. Good specimens may also be had at Grimsby, 
Ontario. 
Catalogue number, 35775, U. 8. National Museum. 
Genus STICTOTRYPA Ulrich. 
Zoarium ramose, not pointed at the base: branches dichotomously dividing, narrow, 
compressed; apertures circular or elliptical, with distinct, usually evenly elevated peri- 
stomes; interspaces flat or concave, composed of horizontally laminated solid tissue. 
Stictotrypa punctipora (Hall). 
1*1. XXII, figs. 7-11; PI. XXIV, figs. 26, 27. 
Stictopom punctipora Hall, Nat. Hist. New York. Pal. II, 1852, p. 157, pi. 40B, figs. 2a-c. 
Mictotrypa punctipora Ulrich, Geol. Survey Illinois, VIII, 1890, p. 394, fig. 13a. 
Hall and Ulrich (op cit.) have figured this species so well that its recognition is a matter 
of no difficulty. The more important of their figures, together with views of the internal 
structure, are given on the plates mentioned above. 
The narrow, bifoliate zoarium, with branches averaging 3 mm. in width, and the ellipti- 
j cal zocecial apertures with a well-marked peristome are so different from other bryozoa of 
this formation that comparison is not necessary. Measuring along one of the rows, 6 to 7 
zocecia may be counted in a space of 2 mm. 
In thin sections the rhomboid or square shape of the primitive zocecium, the blunt infe- 
rior hemiseptum,.and the short cryptostomatous cell are well shown. With respect to 
these characters, thin sections of this species and Diamesopora dichotoma are strikingly 
similar, as a reference to the figures of the internal structure will show. 
The various species of Stictotrypa resemble each other closely, but S. punctipora may 
readily be separated by the fact that the peristome is highest anteriorly, thus giving a 
notched appearance to the aperture. 
Occurrence. — Rather abundant at Lockport, Rochester, and Niagara Falls, N. Y., 
Grimsby, Hamilton, and Thorold, Ontario. 
Catalogue number, 35776, U. S. National Museum. 
