BROWN, RUGOSE CORALS 
47 
gap; furthermore the addition of new plications at the four ends of the fascicles 
is not always contemporaneous in all, or in the opposite corresponding ones, for 
otherwise the lamellae in each equivalent bundle should be equal in number, which 
is not always the case. This bilateral structure of the polyp cells of the Zoan- 
tharia rugosa has been observed by several paleontologists, and been mentioned by 
them as a peculiarity of certain species; but the late Dr. Kunth, of Berlin, was 
the first to demonstrate this bilaterality to be an essential character of all the Zoan- 
tharia rugosa, and to exhibit with clearness the peculiar mode of multiplication 
of the lamellae in this order. If we examine a Streptelasma or a Zaphrentis, we 
find the outer surface of the polyp cells longitudinally striate, by broad convex 
bands or ribs, and by intermediate narrow linear furrows. The furrows correspond 
to the crest-like plications on the inside of the calyces, the ribs to the interstitial 
spaces between them. Three of such longitudinal furrows are, on each of the polyp 
cells, more conspicuous than the others; they correspond to the gaps between the 
bundles of lamellae. In the furrow corresponding to the apertural gap, the other 
furrows from both sides converge at an acute angle, like the barbs of a plume to 
its keel, gradually becoming shorter as they approach the margin of the calyx. 
The two other obvious furrows, corresponding with the lateral gaps, are, on the 
side nearest to the apertural gap, joined by similar parallel furrows extending into 
the apex; on the other side the furrow’s abut against it at an acute angle, and de¬ 
crease in length as they ascend. The central gap is not indicated on the outside, 
because the furrows on both its sides are parallel with it, as new plications are 
never intercalated in this place. 
This interpretation of the structure of these corals stood almost unchal¬ 
lenged for a quarter of a century, till called in question by Duerden in 1902. 
R. Ludwig, in papers published in Id. von Meyer’s “Palteontographica,” 
vols. X and XIV (1865-66), had described and figured certain rugose corals 
as hexameral in symmetry, but his interpretations were so fanciful and 
erroneous that they did not excite much serious consideration. In 1871 
Count L. F. de Pourtales 1 also claimed to have discovered that the rugose 
corals were originally hexameral in symmetry and speaks thus of Ludwig’s 
observations and his own: 
Mr. It. Ludwig has shown that the tetrameral arrangement claimed for the 
Rugosa is only apparent, there being originally six primary septa, but that further 
development in each system is asymmetrical and that tw T o of the systems remain 
generally undeveloped. I had, before having knowledge of Ludwig’s researches, 
come substantially to the same conclusions by the examinations of Lophophyllum 
proliferum Edw. & H., from the Carboniferous formation, a form very suitable 
for the study.When the youngest stage of the coral is examined by cutting 
through the tip of the conical Lophophyllum proliferum, six primary septa and 
six interseptal chambers are found, placed symmetrically on tw r o sides of a vertical 
plane, and unequally developed. 
1 Deep Sea Corals, Ills. Cat. Mus. Comp. Zool., Harvard College, Vol. IV, p. 49. 
