TREMATOPORID^E. 47 
genus exhibit, no diaphragms at all and straight walls, the combination of crinkled walls 
and absence of diaphragms seems a poor generic character. Ptychonema is therefore con- 
sidered a synonym. 
The only associated globular species with which M. benjamini might be confused is Stig- 
matella globata, but the much smaller zooecia of the latter are noticeable with the unaided 
eye. Some specimens of Orbignyella expanse/, might be confused with this form, but the 
presence of curved diaphragms in the former is a distinguishing feature without consider- 
ing the different growth and wall structure. M. benjamini is easily and certainly identi- 
fied by observing the crenulated walls as seen in vertical fractures. Weller a has recently 
described a closely related species, M. corrugata, from the Decker Ferry formation of New 
Jersey. This species, however, has smaller zocecia (10 in 3.5 mm.), a few diaphragms in 
the mature region, and the crenulation of the walls are fewer and much less pronounced. 
The specific name is in honor of Dr. Marcus Benjamin, editor of the United States National 
Museum, to whom the writer is indebted for many courtesies. 
Occurrence. — Not uncommon at Lockport, N. Y. One example of the same form was 
found at Osgood, Ind. 
Catalogue numbers, 35500, 44129, U. S. National Museum. 
MONOTRYPA PEDICULATA 11. sp. 
PI. XVI, f.gs. 10-13. 
Zoarium of small subglobular or pear-shaped pedunculate masses averaging 10 mm. in 
height and half that amount in width; base often slightly expanded. Surface smooth, 
maculae inconspicuous. Zocecia angular, thin walled, to 7 in 2 mm. Acanthopores and 
mesopores wanting. Vertical sections show that the zocecial tubes have somewhat flexuous 
walls and that diaphragms are absent. The walls, however, do not exhibit the crinkling 
usually observed in species without diaphragms. 
The unusual growth obtaining in this species is a character making identification com- 
paratively easy. The initial zocecia are parasitic upon foreign objects and continue to 
grow upward, opening only at the top. In this way the pedunculate form of the zoarium 
is produced, the lower portion of the colony being without apertures and covered with an 
epitheca or pellicular membrane. When new zocecia are interpolated the zoarium assumes 
the normal globular form with the zocecia opening laterally as well as distally. Compared 
further with the associated species of the genus, M. pediculata differs from both in having 
smaller zocecia. Other distinguishing characters are the absence of diaphragms and the 
flexuous walls. 
Occurrence. — Rochester shale, Rochester, N. Y. Osgood beds, Osgood, and near Waldron, 
Ind. 
Catalogue numbers, 44119, 44120, U. S. National Museum. 
Genus DIPLOTRYPA Nicholson. 
Distinguished from Monotrypa. by the presence of mesopores. 
DlPLOTRYPA WALKERI n. sp. 
PI. XIV, figs. 1-5; PI. XXV, fig. 4. 
Zoarium of small masses, irregular, rounded, or pyriform in shape and varying from 
10 to 20 mm. in their diameter. Maculae of larger zocecia and more numerous mesopores 
are present, but are not a conspicuous feature of the smooth surface. Zocecia, 6 in 2 mm., 
sometimes angular but more often somewhat rounded and separated, at least partially, 
by mesopores. Acanthopores wanting. Mesopores numerous, usually small but some- 
times half as large as the zocecia proper. 
" Geol. Survey New Jersey, Pal. Ill, 1903, p. 223, pi. 18, figs. 1-5. 
