| stellata Hall, 
ees, 
ne 
~ 
J. M. Safford on the Genus Tetradium. 237 
dle of each side externally, opposite the lamelle. is 
Figure 1 will serve to give an’ idea of the trans- 98; 
verse, or horizontal section of one of these tubes. 
In the massive specimens the horizontal sections 0? Teukaren® 
of the tubes are square, or nearly so. In all of ™ oridea Vesa iares 
the species the walls are more or less rugose. linear. 
The increase appears to be by the division of the tubes, the 
latter splitting sometimes into two cell-tubes, not unfrequently 
perhaps into four; opposite laminz unite and form the ne 
walls of the young celfs, each of which is in the mean time sup- 
plied with its four rays. ; 
Among the numerous specimens of this genus, which we have 
seen, we have met with but one which shows clearly the pres- 
ence of transverse septa. This is a fragmentary specimen of the 
first species described below. In it the septa are distant about 
twice the breadth of a tube; but few however are seen, and these 
are confined to one end of the mass. 
arately growing 
of i 
Transverse “ey 
I b - 
a line. ‘Transverse septa usually absent. of afew tubes of 7 
y en as the type of the 
genus, occurs abundantly throughout the upper half of the Lower 
mass of woody fibre, and hence the name of the seer £3 
2. T. columnare Hall; Syn. Chetetes columnaris Hall. al. 
of N. Y., vol. i, p. 68, Pl. x1, Figs. 4, 4a—Mr. Hall's species, 
