236 J. M. Safford on the Genus Tetradvum. 
I have thus taken the liberty of offering to your Lordship, as 
the Member of Her Majesty’s Government under whom I serve, 
my view upon a subject of which I have long thought; and 
have only now to request that, in giving it your best attention, 
you will submit this letter to Her Majesty’s Government, an 
particularly to the consideration of the Minister who may be des- 
tined to be charged with the education of the country. 
Geological Survey Office, Jermyn Street, Jan. 25, 1856. 
Art. XVIIL—Remarks on the Genus Tetradium, with Notices of the 
Species found in Middle Tennessee ; by Prof. J. M. SAFFORD, 
A. M., Geologist of the State of Tennessee. 
THE genus Tetradium, has been characterized by Prof. Dana 
in his great work on Zoophytes.* His description and remarks 
are as follows: 
“ Coralla massive, consisting of 4-sided tubes, and cells with 
very thin septa or parietes; cells stellate with 4 narrow laminz.” 
“This genus is near Receptaculites, but differs in having ve 
thin parietes and four distinct rays within the cells, one to eac 
side. The specimen answering to the description, is a fossil of 
uncertain locality in the collections of Yale College, New Haven. 
The cells are about half a line in breadth. The name, from the 
Greek, t#79«s, four, alludes to the quadrate structure.” - 
ar as we know, no further notice has been taken of this 
enus. To us it is of great interest from the fact that individu- 
als, belonging apparently to several species, are not very abund- 
ant in the limestones of the Silurian, or as we shall hereafter term 
it, the Central Basin of Middle Tennessee. 
to nearly a line in breadth; they are very long, and are most 
frequently united throughout laterally, forming massive coralla 
opora. 
he isolated tubes are nearly quadrangular, the edges — 
more or lessrounded. A slight linear depression down the mia 
* United States Exploring Expedition during the years 1838, 1939, 1840, 1841, 
1842, under the command of Charles Wilkes, U.S.N. Vol. 8th, page 701. 
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