24 
whole, is insufficient to break the regular continuity of the fenestrule margins. 
So strong a contrast is presented hy this character to that prevailing in the 
other species that examples of II. lit hostrotono ides can be at once picked out 
with the aid of the naked eye alone. 
The horizontal position of the complete tabulae is maintained with 
great regularity, very rarely an oblique or concave partition occurs. Increase 
by gemmation is frequently well exposed in longitudinal weathered sections, 
with the resulting incomplete chains of corallites. I figure an excellent 
instance of the commencement of such a chain from an angle of a fenestrule 
(PI. IX, Fig. 4), and the gradual building up of the chain. 
In one specimen referred (o this species, the gonopores at the fenestrule 
angles are either single, double, or triple. When more than one is present, 
the additional corallite or corallites arc always much smaller than the 
principal tube. In longitudinal sections, the gonopores can only be 
distinguished from the autopores by a difference in the diameter, and a slight 
difference in the distance apart of the tabulae, which is intermediate between 
that of the autoporal and mesoporal tabulae. 
The only condition of variation that takes place, other than above, is 
in a slight increase or decrease, as the case may be, in the size of the 
fenestrules, and a corresponding difference in the diameters of the three 
forms of corallites composing a chain, but the number of the latter in a chain 
is not increased thereby. 
The points I rely on for the specific separation of H. lithostrotonoides 
are (1) the regularity of the marginal outline of the corallite chains, whereby 
the lateral margins of the autopores and mesopores are brought into one 
alignment, instead of the mesopores occupying re-entrant angles ; (2) the 
consequent absence of a farcimentiform appearance of the corallites. 
In its continuous and barely perceptible farcimentiferous outline of the 
corallite chains, this species resembles II. catennlarius , var. gracilis (Hall), 
Lambe, 1 but the other details of structure in the two forms are quite different. 
The habit of the present coral as regards growth, outline of the fenestrules, 
and general appearance is that of II. escharoides, Lamk., as figured by 
Goldfuss. 2 
Loc. and Horizon. — Beds a and d, Spring Creek, Portions 98, 221 
and 222, Ph. Barton, Co. Asliburnham (•/. M. Curran and C. A. Sussmilch). 
Collections . — Australian Museum and Technical College, Sydney. 
1 Lambe, Conlrib. Canadian Pal., IV, Pt. ], 1890, pi. iii, f. 5, 5 ?. 
2 Goldfuss, Petrefacta Germania.', 1S26, pi. xxv, f. \a-b. 
