0)1 Rhoiiibopora Lcpidodoidroidcs Meek. — Condra. 23 
evident, therefore, that professor Geinitz may have erroneously 
identified two new species, one covering the other, as a single 
described species. 
The object of this brief paper is to announce the positive 
occurrence of the species in the Permian of Nebraska, and to 
briefly delineate its different forms of growth, only one of 
which has been described. Meek's diagnosis is based on the 
young growth, and, as a result, the species is often imperfectly 
known by that form alone. The writer has collected and 
placed in the museum of the University of Nebraska not less 
than fifty pounds, representing several thousands, of nice clean 
specimens. They fall under the following growths : i , young 
form ; 2, old non-montiferous form ; 3, old montiferous form, 
To these may be added the encrusting form which is rarely 
found. From superficial characters, the casual observer would 
try separate the specimens into as many species as there are 
forms of growth. 
Description. — Zoaria ramose, rarely encrusting, "cylindrical 
or slightly compressed, straight to irregular in extent between 
bifurcations, in young and old forms ; surface smooth or mont- 
iferous ; bifurcations at irregular intervals, equal or unequal in 
size, angle variable, usually 60 to 80 degrees. Young forms 
(figs. I, 2, 9, 10.) slender, cylindrical, small, average diam- 
eter less than 2 mm., surface papillose, due to projecting acan- 
thopores. Old forms (figs. 3-6, 8, 11.) larger, more irreg- 
ular, with or without monticules, size variable, diameter 3 to 8 
mm., average 4 or 5mm. ; monticules of montiferous form 
differ in size and arrangement as shown by fig. 5. 
Zooecia curve gradually from central to cortical portions of 
zoarium, through which, in old growths, they continue in near- 
ly straight lines to the apertures ; walls in central or immature 
region thin, in cortical or mature portion thick with acantho- 
pores as a prominent feature; acanthopores or tubuli, as they 
are sometimes called, between zooecial walls, ot two sizes, 
large and small, projecting from the surface when well pre- 
served. Zooecial cavities or cells polygonal in the immature 
region, circular in section and usually smaller in the mature 
portion. Tabulae wanting in most cells, but frequently found 
in old forms. Apertures subcircular in form, arranged (in 
young growth) in vertical and diagonally intersecting series 
