rhinoporidjE. 59 
tudinally 5 to 6 zocEcia may be counted in 2 nun. Thin sections (see PI. XXI, figs. 8-11) 
show that the species has all the internal characters of Nematopora. 
In the small size of the zoarium and in the arrangement of the zocecia they are quite 
different from associated bryozoa with the exception of Acanthoclema asperum (Hall). 
The latter, however, may readily be distinguished by its more robust growth, stronger 
granules or acanthopores, and less regularly arranged zooecia. Internally the two are quite 
different. 
Occurrence. — Rather uncommon in the Waldron shale at Waldron, Ind. More abundant 
in the Rochester shale at all of the localities in western New York and Ontario. 
Catalogue numbers, 35773, 35774, U. S. National Museum. 
THainily RHINOPORID^E TJlrich. 
This family was established provisionally by Ulrich a for the reception of the unique 
Silurian generic type Rhinopora Hall, the bifurcating structures traversing the surface of 
the type species, R. verrucosa, being so different from any known bryozoan that the genus 
could not be classified otherwise. Since that time Mr. Ulrich and the writer, while inves- 
tigating the subject of Paleozoic bryozoa in general, discovered that the family could 
with slight emendation include three other genera, namely, Stictotrypa Ulrich, Diameso- 
pora Hall, and Lichenalia Hall. It was also at this time that the relations and structure 
of the last two genera mentioned were ascertained. Up to this time Diamesopora was 
supposed to be congeneric with Coeloclema Ulrich, an Ordovician genus belonging to the 
Ceramoporidte, while Lichenalia was regarded as a synonym of Fistulipora McCoy. Sticto- 
trypa, although placed under the Ptilodictyonidse, had always proved a troublesome genus 
to locate naturally. The four genera now constituting the Rhinoporidae have a few char- 
acters somewhat at variance, but when reduced to their simplest terms, all agree in pos- 
sessing the following cryptostomatous characters: Oblong or rhomboidal zooecia, direct 
vestibules, and hemisepta, the latter, however, being but little developed. Rhinopora 
is a broad bifoliate type, Diamesopora forms hollow ramose branches, Stictotrypa has nar- 
row bifoliate branches, and the growth of Lichenalia is in semicircular, unilaminate expan- 
sions. 
The first opportunity to publish the new information concerning the Rhinoporidae occurred 
in United States Geological Survey Bulletin No. 173, where, with the kind permission of 
Mr. Ulrich, Nickles and the writer gave short emended descriptions of the family and the 
genera constituting it. For convenience of reference, these descriptions are repeated 
below in their respective places. 
With the emendations pointed out above, the family Rhinoporidae may now be defined 
as follows: 
Zoarium variable in form; zooecia prone along the basal membrane, simple, oblong, or 
rhomboidal; vestibules direct, hemisepta wanting or almost so; front of zocecia below 
vestibule commonly strengthened with solid or vesicular tissue. 
Genus RHINOPORA Hall. 
Two species considered by then authors as members of this genus have been described 
from the Rochester shale. The first, Rhinopora tuberculosa Hall, is now known, from an 
"' jexamination of the type specimen by the writer, to belong to Fistulipora, while the second, 
Rhinopora curvata Ringueberg, seems to be a true member of the genus. 
The generic characters of Rhinopora are as follows. Zoarium forming large, undulating 
bifoliate expansions, eelluliferous on both sides; surface usually smooth, rarely with solid 
monticules, and traversed by slender, rounding, bifurcating ridges, which appear as shal- 
low grooves when the surface is worn; apertures nearly circular, occupying the summits 
of prominent papilla); mesopores present, but closed at the surface; large median tubuli in 
"..he mesotheca. 
« Geol. Survey Illinois, VIIT, 1890, p. 388. 
Bull. 292—06 5 
