198 The American Geologist. April, 1902. 
et striés, qui donnent un aspect spinuleux a la surface. Largeur des 
calices, un quart de millimétre. Planchers horizontaux. 
Siturien (inférieur). Etats-Unis: Cincinnati, (Ohio.) 
Dekayia was adopted in 1879 by H. A. Nicholson, as a 
sub-genus of the genus Monticulipora D’Orb. The following 
is Nicholson's diagnosis : 
“Corallites of two kinds, the larger tubes with thin walls, polygonal 
in shape, and provided with well developed tabule. The smaller tubes 
isolated by the larger corallites, apparently destitute of tabulz, their 
walls greatly thickened, and appearing on the surface as so many 
detached spiniform processes placed at the angles of junction of the 
iarger tubes. Type of the group, Dekayia aspera, E. & H."* s 
On page 298 (Jbid.) he further states that 
“The corallum in Dekayia is truly dimorphic, that the surface- 
columns are the homologues of the spines which are so abundantly de 
veloped in M. (Heterotrypa) tumida, Phill, M. (Heterotrypa) mon- 
iliformis, Nich. and other forms of Monticulipora. * * * Taking 
this view of the subject, the species of Dekayia are principally sep- 
arable from the spiniferous species of Monticulipora (Heterotrypa) by 
the fact that in the former the spines are much reduced in number 
and increased in size, while they are always isolated by the large 
tubes, these latter being of one kind only.” 
In 1882 Mr. Ulrich} included the genus in his family Mon- 
ticuliporide (used here in a wider sense than subsequently), 
with the following definition: 
“Dekayia, Edwards and Haime——Ramose, with branches cylindri- 
cal or compressed. Interstitial cells wanting. Spiniform tubuli few 
but very large. They constitute a conspicuous external feature of 
the zoarium.” 
In 1883 an extended description of the genus was 
given and several new species were added to the two (or one) 
then known. The description of the genus is as follows := 
“Zoarium growing upward from a more or less largely expanded 
basal attachment, into rarely cylindrical, usually flattened branches, 
which occasionally may become subfrondescent. Surface sometimes 
with low monticules, usually, however, nearly even. Cells with poly- 
gonal apertures, sometimes apparently consisting of one kind only, 
but more commonly a few interstitial cells may be detected, which 
are more especially developed between the individuals constituting the 
groups of larger cells, that always furnish a more or less conspicuous 
feature of the surface. Cell-walls always thin, sometimes excessively 
so, there being but one species (D. trentonensis n. sp.) [placed by 
Nickles and Bassler in Dekayella] in which the tube walls as the 
* Paleozoic Tabulate Corals, 1879, Pr — 292. 
+ Tour, Cin, Soc. Nat. Hist., vol. v, p. 
t Jour. Cin, Soc. Nat. Hist., vol, vi, ry a8. 
