CORALS AND BRYOZOA. 
207 
moderately thick, sub-equally elevated, and having on one side two denticula- 
tions. Inter-apertural space flat, smooth or with indications of the vesicles 
below. Surface marked by prominent, conical monticules, the centers of 
which are distant about 7 mm., and have cell apertures larger than the 
others, more oblique and pustuliform, often presenting a confused appear¬ 
ance. When the frond is worn or macerated the surface presents a much 
different aspect from that of well preserved specimens; the cell apertures 
are obscurely trilobate ; the peristomes are strong and equally elevated; the 
inter-apertural space is occupied by minute angular pits, the margins of 
which are elevated a little less than the peristomes. 
In having conspicuous opercula this species resembles L. operculata and 
Fistulipora serrulate/,; from the former it may be distinguished by the more 
prominent and more frequent monticules, the equally elevated peristomes, the 
absence of bullae on the inter-apertural surface, and the prominent apertures at 
the center of the monticules; in that species there is a circular space destitute 
of cell apertures: from F. serrulata it may be distinguished by the more promi¬ 
nent monticules, more closely disposed cell apertures, the presence of denticula- 
tions and the absence of mesopores; in the pustuliform apertures at the center 
of the monticules it resembles L. conulata of the Upper Helderberg group, but 
the mode of growth is different, the monticules are much larger and more 
distant, and the ordinary cell apertures are not pustuliform: from the other 
species, at present known, it may be distinguished by its conspicuous opercula 
and the prominent pustuliform cell apertures of the monticules. 
Formation and locality. Hamilton group, York, Livingston county, N. Y. 
Lichenalia tessellata, n. sp. 
h»OT FIGURED. 
Zoarium consisting of flattened expansions or of masses formed by the accretion 
of successive layers of growth; fronds observed from 2 to 5 mm. in thick¬ 
ness ; epitheca very thin and, on the specimens examined, not strongly 
wrinkled concentrically, as in nearly all other species. Cells tubular, 
apparently polygonal, generally rectangular to the surface, walls thin, 
