190
THE SPIDERS OF EPPING FOREST.
Fig. V. Caput in profile, showing striae on falx.
Fig. VI. Caput in profile, showing basal protuberance of falx (a.)
Fig. VII. Leg a. Coxa.
b. Trochanter. e. Tibia.
c. Femur. f. Metatarsus.
d. Patella. g. Tortus.
Fig. VIII. Palpus, male.
a. Maxillary plate. e. Tibia.
b. Trochanter. f. Tarsus.
c. Femur. g. Palpal organs.
d. Patella.
Fig. IX. Vulva, without clavus.
Fig. X. Hind portion of thorax of Phyllonethis, showing striations
Fig. XI. Vulva with Clavus (a.)
II.—CLASSIF1CATION.
In order to satisfactorily sub-divide this difficult and
complex Order it becomes absolutely necessary to enter into the
consideration of certain exotic forms. A system founded upon
a limited fauna, such as that of the British Isles, would of
necessity be more or less artificial and misleading, and certain
groups which might then appear quite distinct, would become
almost inseparable upon the insertion of exotic species. The
difficulty of establishing a satisfactory system of classification is
vastly increased by the widely diverse opinions held by various
authorities as to the comparative importance of certain portions
of the structure of the creatures under consideration. Again,
unless certain links in the chain of evolutionary development have
disappeared, classification becomes an impossibility, species,
genera and families merging into each other to form perplexing
and almost unmanageable series. In the case of the Araneae so
many of the earlier forms remain, that groups whose more highly
specialised representatives are totally dissimilar become insepar-
ably linked by intermediate species and defy any attempt at a
satisfactory broad sub-division by reason of the gradual develop-
ment and elimination of those structural characteristics upon
which our systems are based. With the discovery of new species
the classification of a group becomes as a rule more complex and
difficult, forms being thus found to bridge over the gaps between
previously distinct genera and families. Were our knowledge
of any group absolutely complete, both in regard to modern and
extinct forms, classification would become quite impossible, as we should