NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
217 
DIPLOPHOLEOS SAGITTELLARIUM, new species. 
Plate 34, figs. 5-7. 
Description. — The zoarium incrusts shells and bryozoa. The zooecia are hex- 
agonal, indistinct, with their mural rims confluent; the cryptocyst is shallow, 
oblique toward the opesium, very finely granulated, longer than the opesium; the 
polypidian convexity projects but little, occurs below the opesial denticles, and is 
elevated almost vertically; the opesiular openings are large, round; the opesium 
is transverse in appearance (with the opesial openings), semilunar, narrowed ante- 
riorly by two lateral teeth above the opesiules. The ovicell is an inconspicuous 
distal convexity. The onychocellarium is straight, much larger than the zooecium, 
with the form of a small leaf of the plant Sagittaria , terminated by a large mandi- 
bular area; its opesipm is oval, the point at the top, entire or crenulated. Dimor- 
phism is manifested by large and small zooecia. 
M easuremei 
V aviations. — The large zooecia occur less frequently. Well preserved speci- 
mens have the aspect of Stvganoporella; but if the specimen is turned and the 
interior is examined, the internal divisions characteristic of SteganoporeUa. limit- 
ing the polypidan tube, can not be seen (fig. 7). 
Good specimens also show that the polypidian convexity is elevated almost 
vertically as in Tkalamoporella. and when the opesial denticles are united with the 
convexity, such examples have then a constitution identical with that of this genus. 
The ovicells however are very different (fig. 5). 
Most often the polypidian convexity is broken or not developed, but the 
opesiular openings are always quite distinct (fig. 5). 
The zooecial dimorphism has to do perhaps with a double system of nutrition. 
Affinities. — Its zooecial dimorphism and the form of its onychocellarium clearly 
characterize this beautiful species. It differs from Diplopholeos sagittarium in 
the smaller dimensions of its onychocellarium and in the absence of opesial denticles 
in this organ. 
Small zooecium 
Onychocell 
fLon=0.70 mm. 
