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 di\asion 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. 



