342 On new Species of Monticuliporoid Corals. 
observer of a similar structure characteristic of the genus 
Stenopora (Lonsdale). Mr. Ulrich draws attention to a like 
feature in his description of a Cincinnati-group species of 
Dekayella—D, obscura, Ulrich (Journ. Cincinnati Soc. Nat. 
Hist. vol. vi. p. 150). 
On leaving the axial region the tubes rapidly thicken 
towards the surface, the spiniform corallites being seen at 
frequent intervals piercing the corallum and intermingling 
with the ordinary corallites. The spiniform corallites appear 
to originate in the axial region of the corallum, as they may 
be seen in sections cut as deeply as it is possible to make them 
without destroying the walls of the tubes. 
It may be well here to enumerate the chief characters which 
separate this species from the only two known to the writer, 
viz. Dekayella Ulrichii, Nicholson *, and D. obscura, Ulrich— 
both from the Cincinnati Group of Ohio. From the former 
of these the present type may be distinguished as follows :— 
by its much more robust habit of growth, by the possession 
of monticules, and by the much greater number of its tabule 
and spiniform corallites. The exceedingly small and delicate 
corallum of D. obscura, Ulrich, would be sufficient alone to 
differentiate it from D. robusta, and added to this the great 
development of the tabule and spiniform corallites in the 
latter make the distinction between the two forms sufficiently 
clear. 
Formation and Locality. Cincinnati Group, Cincinnati, 
Ohio. 
* EXPLANATION OF PLATE XII. 
ig. 1. Monotrypa macropora, Foord: upper surface of corallum. Nat. 
size. 
Fig. 1 a. Side view of the same specimen. 
Fig. 1b. Tangential section of this species, enlarged about 20 diameters. 
Fig. 1c. A few cells, enlarged about 50 diameters. 
Fig. 1d. Longitudinal section, enlarged about 15 diameters. 
Fig. 2, Dekayella robusta, Foord: corallum, showing monticules. Nat. 
size, 
Fig. 2a. Tangential section of this species, showing the two series of 
spiniform corallites a, a. Enlarged about 30 diameters, 
Fig. 2b. Two cells, enlarged about 50 diameters. 
Fig. 2c. Longitudinal section, showing at @ one of the spiniform coral- 
lites. Enlarged about 20 diameters. 
Fig. 2d. Portion of the same, showing more clearly the periodic inflation 
of the walls of the tubes. Enlarged about 50 diameters. 
Fi 
> 
* =Monticulipora (Heterotrypa) Ulrichti, Nicholson (‘The Genus 
Monticulipora,’ Nicholson, p. 181, fig. 22, 1881). 
