CORALS AND BRYOZOA. 
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the primary rachis; this mode of growth is continued indefinitely, the 
fronds covering a comparatively large area. Cell tubes sub-cylindrical, 
sinuous, especially near the base, the attached portion hat, the free portion 
convex; length about 2 mm., width .50 mm., turning abruptly outward at 
the extremities, the apertures being parallel with the axis of the branch 
and broadly oval, generally alternating, occurring at intervals of about 
1.33 mm.; for a short distance they are nearly parallel with the rachis, then 
diverging at an angle of from thirty-five to forty degrees, margins of the 
branches in contact, but not coalescing, the end of each succeeding cell 
tube projecting beyond the previous one, giving a serrated appearance to 
the margins of the frond. In well-preserved specimens the cell tubes are 
strongly annulated and generally obscurely angular along the middle, giving 
the annulations the appearance of a row of nodes; on some portions of the 
frond the cells are not angular, but the annulations still have somewhat 
the appearance of nodes along the middle of the tube; the annulations are 
broad, abruptly rounded, three in the space of 1 mm., with indications of 
faint longitudinal striations. 
This species forms comparatively large fronds, fragments occurring nearly 
100 mm. in length; numerous branches apparently originate at a common 
base; on different fronds and on different portions of the same there 
is a great irregularity in the frequency of branching; on one specimen there 
are five widely diverging branches in the space of 60 mm.; on another 
frond in the same space there are fourteen branches, diverging at an angle 
of thirty degrees, on one portion three branches in the space of 7 mm. The 
branch becomes gradually narrower toward the extremity, the last cell being 
terminal and extending beyond all the others. All the specimens observed 
occur upon the shells or casts of Cephalopoda. 
This species may be distinguished from R. nodata by the narrower cell tubes, 
and the much less prominent annulations and nodes; from Hederella conferta by 
the difference in the character of the rachis, the more regular arrangement of 
the cell tubes, and the prominent annulations. 
Formation and locality. Hamilton group, Cazenovia, Madison county, N. Y. 
