METHODS. 
17 
large or small they may be, and are therefore biometrically much more correct 
than those obtained by the method generally in use. In this Report such fre- 
quency-curves, which are biologically more correct, are extensively made use of. 
7. Nomenclature of the spicules. 
I use the same names for the spicules as those employed by F. E. Schulze 
and other authors. The few new names given are explained where they first 
occur. I find F. E. Schulze’s division of the amphidiscs into the three groups 
macramphidiscs, mesamphidiscs, and micramphidiscs by no means universally 
applicable and have divided the different kinds of amphidiscs found in each 
species according to their morphological and biometrical characters, independ- 
ently of and without regard to the arrangements of them in other species. I 
have, however, retained Schulze’s names, because only a very small fraction 
indeed of the Amphidiscophora actually growing on the sea-bottom are 
known, and it would be premature to propose a new general arrangement of 
these spicules, and to replace Schulze’s names by others. 
