142 PACKARD—CLASSIFICATION OF ARTHROPODA.  [April3, 
knowledge. For this he is willing to do his utmost in any and 
every direction that is open to him. The motive which controls 
the philosophical skeptic is his fear of a false step. He is indis- 
posed to stir at all until secure of his footing. The mind when in 
a scientific attitude is patient even of known error, if only it can be 
made the basis of a really good working hypothesis that will help 
the inquirer forward, and which may then become susceptible of 
revision and correction. Numberless instances can be given in 
which this process has led to valuable results. In fact, most of 
man’s scientific knowledge of nature is owing to it. But sucha 
method is repugnant to the philosophical skeptic, whose attitude 
damps all advance unless it can be carried on from the beginning 
under conditions of perfection—in other words, under conditions 
which are impossible in the early stages of almost every inquiry. 
30 LeEpBuRY Roap, Lonpon, W., March, 1903. 
HINTS ON THE CLASSIFICATION OF THE ARTHRO- 
PODA; THE GROUP A POLYPHYLETIC ONE. 
BY ALPHEUS S. PACKARD. 
(Read April 8, 1903.) 
Of the ten or twelve chief groups or phyla into which the animal 
kingdom is subdivided by systematists, nearly all except those of 
the old groups Vermes and the Arthropoda are acknowledged to be 
fairly well limited. There is a general agreement of opinion as to 
the naturalness and monophyletic origin of the Protozoa, Porifera, 
Coelenterata, Echinodermata, Mollusca and Chordata. Those of 
the ‘‘ worms’’ and the great group Arthropoda are still the cause of 
more or less difference of opinion. 
The group Arthropoda was established by Siebold in 1848, but in 
late years, with the increase in our knowledge of the morphology 
and embryology of the Arthropodan classes, especially of the Tri- 
lobita, Merostomata, Malacopoda (Peripatus) and Myriopoda, there 
has been expressed by several zoologists the opinion that the Arthro- 
podan phylum is a more or less artificial one, and should be sub- — 
divided into more natural groups—z.e., that it is composed of 
several phyla. 
Were it only a matter of convenience, the great group Arthro- 
