g organs developed on the basal joints of the
limbs, which differ in position and character in different genera (see
Pocock, 27). Scorpions copulate with the ventral surfaces in contact.
The eggs are fertilized, practically in the ovary, and develop _in
situ_. The young are born fully formed and are carried by the mother
on her back. As many as thirty have been counted in a brood. For
information as to the embryology of scorpions, the reader is referred
to the works named in the bibliography below. Scorpions do not possess
spinning organs nor form either snares or nests, so far as is known.
But some species inhabiting sandy deserts form extensive burrows. The
fifth pair of prosomatic appendages is used by these scorpions when
burrowing, to kick back the sand as the burrow is excavated by the
great chelae.

References to works dealing with the taxonomy and geographical
distribution of scorpions are given at the end of this article (28).

Section [beta]. _Epectinata._--The primitive distinction between the
mesosoma and the metasoma wholly or almost wholly obliterated, the two
regions uniting to form an opisthosoma, which never consists of more
than twelve somites and never bears appendages or breathing-organs
behind the 4th somite. The breathing-organs of the opisthosoma, when
present, represented by two pairs of stigmata, opening either upon the
1st and 2nd (Pedipalpi) or the 2nd and 3rd somites (Solifugae,
Pseudo-scorpiones), or by a single pair upon the 3rd (? 2nd) somite
(Opiliones) of the opisthosoma, there being rarely an additional
stigma on the 4th (some Solifugae). The appendages of the 2nd somite
of the opisthosoma absent, rarely minute and bud-like (some
Amblypygi), never pectiniform. A prae-genital somite is often present
either in a reduced condition forming a waist (Pedipalpi, Araneae,
Palpigradi) or as a full-sized tergal plate (Pseudo-scorpiones); in
some it is entirely atrophied (Solifugae, Holosomata, and
Rhynchostomi). Lateral eyes when present diplostichous.

_Remarks._--The Epectinate Arachnids do not stand so close to the
aquatic ancestors of the Embolobranchia as do the Pectiniferous
scorpions. At the same time we are not justified in supposing that the
scorpions stand in any way as an intermediate grade between any of the
existing Epectinata and the Delobranchia. It is probable that the
Pedipalpi, Araneae, and Podogona have b