BATOSTOMELLID^. 33 
Zooecia thin walled, 6 in 2 mm., polygonal to rounded, the outline depending upon the 
number of mesopores intervening. Mesopores open at the surface, numerous, and because 
of their frequency the zooecia are seldom in contact. In the macula? often three rows of 
mesopores separate adjoining zooecia. Acanthopores large and numerous, 3 to 5 usually 
encircling a zooecium and often indenting the zoo?cial cavity, thus giving a petaloid appear- 
ance seen at the surface and in sections. 
Internal characters. — This species affords very pretty thin sections, the tangential especially 
so when showing the full development of acanthopores and mesopores. In such a section the 
acanthopores are seen to be large, sometimes as much as 0.1 mm. in diameter, and to show 
the central canal distinctly. Zooecia as a rule 0.20 mm. in diameter and with walls slightly 
thicker than those of the mesopores. Vertical sections indicate that the axial region is short 
and the bend to the peripheral often quite abrupt. With the inception of the latter region 
mesopores are developed. Diaphragms are practically wanting in the zooecial tubes, but 
are quite abundant in the mesopores, being placed at intervals varying from one-half to a 
whole tube diameter. Some of the numerous acanthopores are cut by vertical sections 
which show clearly the internal features of these structures. 
The incrusting habit of growth, smooth surface, size of zooecia, abundant and unusually 
large, conspicuous acanthopores and numerous mesopores eaus:> this species to be easily 
identified. The only form with which it might be confused is the associated and very 
abundant L. mvltiporum, but the latter has much smaller zooecia and unusually numerous, 
small mesopores and acanthopores to distinguish it, irrespective of the different internal 
structure. Certain forms of L. asperum resemble the two lamellate species L. circinctum 
and L. explanatum. The similarity, however, is only in method of growth, the other specific 
characters being quite different. 
Occurrence. — Abundant in the Rochester shale at Lockport, Rochester, Niagara Gorge, 
and near Lewiston, N. Y., and at Grimsby, Ontario. Not uncommon in the Osgood beds 
at Osgood, Ind. 
Catalogue numbers, 35504, 35505, 44124, U. S. National Museum. 
LlOCLEMA EXPLANATUM n. sp. 
PI. XIII, figs. 8-10; PI. XXVI, fig. 4. 
Zoarium, a laminar expansion composed of a single layer varying from several millimeters 
to a centimeter or more in thickness, or a more or less rounded mass formed of several super- 
posed layers; under surface concentrically wrinkled; upper surface celluliferous, smooth, 
with maculae inconspicuous. Zooecia subcircular, those in the intermacular spaces averaging 
0.25 mm. in diameter and about five occurring in 2 mm. Mesopores large, rather numerous, 
and usually isolating the zooecia. Acanthopores small, inconspicuous, and generally seen 
only in thin sections; few in number, an average of two to a zoarium, although sometimes 
as many as four may be present. 
The principal internal characteristic of this species is the loose tabulation of both the 
zooecial tubes and the mesopores and in this respect L. explanatum differs from all the associ- 
ated forms of Lioclema. In the zooecia the diaphragms vary in distance from each other 
from a tube diameter to three or more times that dimension. The same variation is exhibited 
in the mesopores, but because of their narrower diameter these appear more closely tabulated. 
The laminar growth, large zooecia, and comparatively few and small acanthopores, dis- 
tinguish this species externally from the associated forms of the genus, while the internal 
characters, as mentioned above, are quite different from any of the other species. Associ- 
ated laminar species, such as N icholsonella jlorida (Hall), will not be confused because of 
their floriform apertures and solid interzooecial spaces. Probably the closest ally is L. 
asperum, but the different tabulation, larger zooecia, explanate growth, and especially the 
much less numerous and smaller acanthopores, are points of difference. 
Occurrence. — Rochester shale, not uncommon at Rochester, N. Y. Osgood beds, rare at 
Osgood, Ind. 
Catalogue number, 35503, U. S. National Museum. 
