that of the
crustacean Laemodipoda. The genital pores are situate at the base of
the 7th pair of limbs, and may be repeated on the 4th, 5th, and 6th.
In all known Pantopoda the size of the body is quite minute as
compared with that of the limbs: the alimentary canal sends a long
caecum into each leg (cf. the Araneae) and the genital products are
developed in gonocoels also placed in the legs.

[Illustration: FIG. 43.--One of the Nymphonomorphous Pantopoda,
_Nymphon hispidum_, showing the seven pairs of appendages 1 to 7; ab,
the rudimentary opisthosoma; s, the mouth-bearing proboscis.

From Parker and Harwell's _Text-book of Zoology_, after Hoek.]

The Pantopoda are divided into three orders, the characters of which
are dependent on variation in the presence of the full number of legs.

Order 1. (of the Pantopoda). Nymphonomorpha, Pocock (nov.) (fig.
43).--In primitive forms belonging to the family _Nymphonidae_ the
full complement of appendages is retained--the 1st (mandibular), the
2nd (palpiform), and the 3rd (ovigerous) pairs being well developed in
both sexes. In certain derivative forms constituting the family
_Pallenidae_, however, the appendages of the 2nd pair are either
rudimentary or atrophied altogether.

Two families: 1. Nymphonidae (genus _Nymphon_), and 2. Pallenidae
(genus _Pallene_).

Order 2. Ascorhynchomorpha, Pocock (nov.).--Appendages of the 2nd and
3rd pairs retained and developed, as in the more primitive types of
Nymphonomorpha; but those of the 1st pair are either rudimentary, as
in the _Ascorhynchidae_, or atrophied, as in the _Colossendeidae_. In
the latter a further specialization is shown in the fusion of the body
segments.

Two families. 1. Ascorhynchidae (genera _Ascorhynchus_ and
_Ammothea_); 2. Colossendeidae (genera _Colossendeis_ and
_Discoarachne_).

Order 3. Pycnogonomorpha, Pocock (nov.).--Derivative forms in which
the reduction in number of the anterior appendages is carried farther
than in the other orders, reaching its extreme in the _Pycnogonidae_,
where the 1st and 2nd pairs are absent in both sexes, and the 3rd pair
also are absent in the female. In the _Hannoniidae_, however, which
resemble the _Pycnogonidae_ in the absence of the 3rd pair in the
female and of the 2nd pair in both sexes, the 1st pair are retained in
both sexes.

Two families: 1. Hannoniidae (genus _Hannonia_); 2. Pycnogo