337 
The buttons of C. calcarea have the two lateral holes consider- 
ably larger than the terminal ones, while in brevidentis the holes 
are all of nearly the same size; upon the whole the buttons are 
more siender and elegantly shaped in calcarea than in brevidentis. 
Also the knobs along the edge of the buttons are more numerous 
(12) in calcarea than in brevidentis (10) (Figs. 26.b—c). This I find 
to be a perfectly constant character, and on looking over preparations 
of the calcareous deposits of the two species one cannot help being 
struck with the difference and it must seem impossible that specimens 
containing so strikingly different calcareous bodies could belong to 
one and the same species. (The figures represent the typical form 
of the buttons; forms with more holes and knobs, often rather ir- 
regular, are by no means rare, but also in these the original type 
is nearly always discernible). The buttons are also much more 
numerous in calcarea than in brevidentis, the skin being of quite 
a chalky consistence in the former. On the other hånd, the larger 
plates of the skin are very much scarcer in calcarea than in bre¬ 
videntis, sometimes apparently wholly wanting. 
Further, the cups are different in the two species. In calcarea 
they are provided with numerous knobs on both sides, in brevidentis 
they are knobbed only on the upper side, the underside being 
smooth (Figs. 26, a, d). 
From the description and figures of the calcareous bodies of 
the specimens from Juan Fernandez recorded by Ludwig under 
the name of Coloch. brevidentis it seemed very probable that these 
specimens really belonged to C. calcarea and not to brevidentis. 
Dr. W. Arndt of the Berlin Museum having kindly sent me one 
of these specimens I am in a position to say definitely that they 
are not brevidentis; the calcareous spicules agree completely with 
those calcarea and thus the Juan Fernandez form must, for the 
present at least, be referred to C. calcarea. As it is a littoral form, 
which can be transported on floating algae, the occurrence of the 
species at New Zealand and Juan Fernandez is not so very sur- 
prising. But it is to be expected that it will prove to occur also 
on the other subantarctic localities. 
Vidensk. Medd. fra Dansk naturh. Foren. Bd. 79. 
22 
