98 SECTIONAL ADDRESSES, 
often been missed. Classifications have also been given claiming to 
be genetic, but too often all that has been done has been the placing in 
the same group or class, forms that have reached a parallel evolutional 
stage, and since many of the more conspicuous evolutional stages 
appear to be reached at approximately the same time, even though along 
different lines, such a classification is chronological rather than bio- 
plogical. From the geological standpoint a chronological classification 
‘is valuable, but the biological side must not be ignored. Thus we have 
seen in the classification of the Graptoloidea, Climacograptus and 
Diplograptus are both included in the family of the Diplograptide, 
presumably because they are both biserial and have both attained the 
scandent position of growth; they have no other connection and appear 
to have totally different lines of descent. The same is to a large 
extent true of Pompeckj’s classification of the Calymenes.1®° Thus 
Pompeckj divides the Calymenes proper into two sub-genera, Pharo- 
stoma and Calymene. ‘The forms included under the s.g. Pharostoma 
are stated to be characterised by the presence of long genal spines and 
the termination of the facial suture at the posterior margin. These 
two are closely connected, for the presence of genal spines seems to 
inhibit the facial suture coming out at the genal angle as in the s.g. 
Calymene; hence if, as Pompeck] himself suggests, the possession of 
spines is a primitive character, it carries with it a notable stage in the 
development of the facial suture, since until the spines have dis- 
appeared the facial suture cannot come out at the genal angle. Hence 
the rounding of the angle and the position of the termination of the 
facial suture together mark an evolutional stage that is regarded as 
characteristic of the s.g. Calymene. He also places Calymenes of the 
tristami type in a totally different section from the Calymenes of the 
type of C. cambrensis (Calymene s.s.), for he holds that the lobing of 
the glabella is so different that ‘relationship is not to be thought of,’ 
whereas I hope to be able to show that, looked at evolutionally, these 
forms may be regarded as belonging to different points along a special 
trend line, that of evolution of the glabella lobes, and the appearance 
of bifurcation in the glabella furrows upon which he lays such stress 
as a feature of importance in classification appears to me to be a neces- 
sary stage in the lobal evolution, and therefore only highly developed at 
a certain stage. 
On the other hand, Calymene caractaci, which he places in the 
same group as C. cambrensis, apparently chiefly on the grounds of the 
course of the facial suture and number of glabella lobes, does not 
appear to me to be so closely related from the genetic point of view, 
since theses two differ markedly in other characters that must, I think, he 
considered ‘ essential,’ and therefore belong more likely to different 
species-groups. 
A glance at the table given at the end of his paper will serve to show 
how largely this classification is chronological. It is probably true that 
the greater number of our fossil ‘ genera’ at the present day are poly- 
phyletic, and cut across true lines of evolution, as can be demonstrated 
10 1898, Pompeckj, J. F. ‘On Calymene Brongniarti.’ Jahrb. f. Mineral., 
Geol, & Pal., vol. i, p. 187. 
