8 
very small or entirely obliterated; and in the former case, the “rods” 
forming their walls are two at each end, meeting and coalescing in the 
middle; in the latter case, the walls have a solid and homogeneous appearance ; 
the tabulae are complete. H. elegans, E.-B., also possesses a false columella, 
and the edges of the autopores are strongly festooned by the septa, of which 
there are two cycles only to each visceral chamber. H. quadrata, E.-B., 
again has a strongly developed false columella, and both mesopores and 
gonopores are shown in the figure. In the last species described, H.jacovickii, 
E. de Waldheim, the corallum is built with remarkable regularity, and more 
or less resembles a Favosites ; mesopores and gonopores are both present, but 
the spiniform septa do not coalesce at the calicinal centres. 
1873. — Lindstrom (G). 1 — This author, in describing Swedish Lower 
Silurian corals, mentions an example of II. escharoides , Lamk., from Dalarne, 
in which the spiniform septa unite at the calicinal centres to form irregular 
spongy masses, thus confirming Eischer-Benzon’s description of his false 
columella. 
1873. — Lindstrom (G.). 2 — The same writer, in an article on the 
“ Anthozoa Tabulata,” described two forms of zooids in Halysites as in 
Heliolites. lie remarked that between the larger zooids (autopores), with 
their widely-spaced tabulae, occurred smaller vesicular tabulate tubes 
(“ ccenencliyma,” or our mesopores). 
1876. — Rominger (C.). 3 — Dr. Rominger united II. catenularia , Linn., 
II. escharoides, Lamk., and II. labyrinthica, Goldf. He recognised in a 
generic sense twelve septa (“longitudinal crests”) and “flat diaphragms” 
(tabulae), but did not make any reference to corallites of more than one 
order, although in one figure 4 at least mesopores are shown. 
1879. — Nicholson (H. A.). 5 — At the time my deceased friend wrote his 
masterly work on the “ Palmozoic Tabulate Corals,” he had not seen 
Dr. Eischer-Benzon’s paper, and he restricted his observations to the two 
typical Edwardsian species. He distinguished II. catenularia by the presence 
of zooids of two orders and no septal spines, and II. escharoides by the 
possession of corallites of one order only, and these with twelve septal spines 
1 Lindstrom, Ofvers. K. Vet.-Akad. Forhandl. Stockholm, 1873, No. 4, p. 25. 
3 Lindstrom, Loc. cit., p. 1G. 
3 Rominger, Report Geol. Survey Michigan— Lower Peninsula, 1873-76, III, Pt. 2, 187G, p. 78. 
4 Rominger, Loc. cit., pi. xxix, f. 2. 
5 Nicholson, Tab. Corals Pa Period, 1870, pp. 22G-231 
