1903. No. 10. REVISION DER MITTELSILURISCHEN HELIOLITIDEN. 23 
Erst in seiner Kritik meiner Arbeit, worin ich die Protaraea und 
verwandte Formen als eine Unterfamilie der Heliolitiden aufstelle, ent- 
wickelt Lindström näher seine Auflassung dieser Verhältnisse auf folgende 
Weise: 
»According to Dr. K. the Coccoseridae form the first »Unterfamilie« 
of the Heliolitidae. I am certainly convinced that this assertion militates 
against all well founded and scrutinized facts. In spite of some super- 
ficial similarity the interior structure of the sceleton of the Coccoseridae 
is of so fundamentally different a nature that they must decidedly 
be separated from the Zeliolitidae and placed as a coordinate family, 
alongside with these and other palaeozoic corals!. While in all the 
genuine //eliolitidae the composite polyparium consists of both vertical 
and horizontal elements, as well known, which through their variability 
originate a multiplicity of forms, in the Coccoseridae, on the other hand, 
there prevails, as a rule, the vertical element exclusively to the horizon- 
tal, which only in a few instances in the genus Acantholithus appears 
as scarce tabulae in the coenenchyma. In all the numerous specimens 
of the Coccoseridae which I have been able to examine the polyparium 
is a compact mass of closely packed vertical trabeculae of the same sort 
that I have called baculi. They are considerably larger than those 
which sparingly occur in the Proporae, these being together with Dzploe- 
pora the only Heholitidae in which they are found. Besides, there are 
other important distinctions between the two families. In the Cocco- 
seridae there is a total want of a distinct theca around the calicles. 
Their septa in all the three genera of which they, according to my views, 
consist, are moreover of a type so entirely peculiar and deviating from 
the thin lamellae of the Heliolitidae, that they alone would have been 
sufficient for a separation. In the Coccoseridae each septum is a thick 
lamina, in its margin subdivided in relatively thick lobules, all of equal 
size, curved upwards towards the centre of the calicles and each lobule 
is composed of microscopic fibrillae, diverging at all sides from a central 
axis. Each lobe thus in fact is a curved baculus though adhering with 
its basis to a sort of rhachis common to them all. There is thus the 
important difference between these two sorts of septa, that in the He/io- 
litidae the lamella consists of one set of parallel fibrillae above each 
other, while in the Coccoseridae the septum is dissolved into a series of 
fibrillous, oblique baculi.« 
1 Lindström nennt in seiner Arbeit die Coccoseriden eine Familie, coordinate to Helio- 
litidaee, schwächt aber dies hier ab durch die Zufügung »and other palaeozoic corals«, 
