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196 Ill. PROLES ARACHNES<br />
25. THE ORDER CYPHOPHTHALMI<br />
( 5) The use of a spermatophore<br />
(6) The absence of a genital operculum<br />
(7) The tubercles for the odoriferous glands<br />
(8) The tarsal glands of the males<br />
(9) The anal glands of the males<br />
( 1 0) The length of life<br />
197<br />
FIG. 75. Map showing the distribution of Cyphophthalmi.<br />
The resemblances between the two taxa were close enough to unite<br />
them when the Opiliones were less well known and the Cyphophthalmi<br />
were scarcely known at all. Their separation follows fuller knowledge of<br />
their structure and behaviour, and this, as always, has tended to emphasize<br />
distinctions rather than similarities. It is common taxonomic<br />
experience that the splitting of any group is a consequence of meticulous<br />
study and a recognition of the significance of differences.<br />
The most obvious similarity between Cyphophthalmi and Opiliones<br />
is the presence of odoriferous glands in the prosoma. While it is true that<br />
all Opiliones possess odoriferous glands, it is not in logic true that all<br />
possessors of such glands are Opiliones.<br />
Another resemblance is seen in the form of the ovipositor, so that there<br />
is an undeniable relation between the two orders, with the addition that<br />
the Cyphophthalmi resemble the Laniatores-and especially the Oncopodidae-more<br />
closely than they resemble the Palpatores, while<br />
remembering that they also resemble the Notostigmata among the<br />
Acari.<br />
The differences between the Cyphophthalmi and the Opiliones may<br />
be summarized in short form thus:<br />
It is maintained that the above characteristics are sufficient in<br />
number, in detail and in principle to justify the creation of the order.<br />
This is a step of which some will undoubtedly disapprove, and to the<br />
strength of their disapproval the following concession may be offered as<br />
a general conclusion.<br />
From an ancestral group of proto-Opiliones there evolved the primitive<br />
cryptozoic order that has been described. Either from the same<br />
ancestry or from some early Cyphophthalmi there evolved the somewhat<br />
less photonegative, less thigmotropic order which increased in<br />
dimensions, forsook the cryptosphere, abandoned the spermatophore<br />
and acquired the use of a true intromittent male organ. There is sufficient<br />
suggestion that a similar course of evolution has occurred among<br />
other sets of related arachnid orders to support this interpretation of the<br />
phylogeny of the Cyphophthalmi.<br />
In an elementary classification, based on similarities of external<br />
appearance, the Cyphophthalmi may well be left to obscurity among<br />
the Opiliones; but in a phylogenetic classification, which attempts to<br />
reflect the course of evolution, the distinction between the free-living<br />
and specialized Opiliones and their primitive, cryptozoic forerunners<br />
is too conspicuous to be overlooked. It would be irrational to do so.<br />
( 1) The sculpturing of the exoskeleton<br />
(2) The nature of the bodily segmentation<br />
(3) The position of the eye (when present)<br />
( 4) The form of the penis
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