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Transactions of the Society. 
form, and often an importance quite unknown among insects, but 
found also in some other groups of the Araohnida, for instance the 
Scorpions and scorpion-like animals, where they attain great size and 
are called the pedipalps, a name which has lent itself to the nomencla- 
ture of the order which most of them belong to. Moreover, there 
is a tendency among the writers of modern text-books, in order to 
harmonise the terminology all through the Arachnida, to call the 
palpi “ pedipalps ” throughout the group ; this does not appear 
to be desirable, because, although the palpi are pedate in the small 
group of the Scorpions and their allies, yet in the great order of 
the Spiders, and in the vastly greater order of the Acarina — which 
in variety, in number of species, and in number of individuals 
probably enormously exceeds all the remainder of the Arachnida put 
together — the palpi are not pedate in any way. It seems tome by no 
means a happy idea to adopt a name which is distinctly misleading in 
regard to the immense majority of the class because it is appropriate 
in the case of a small number of rather exceptional creatures, which 
are included in it. So great is the importance of the palpi, as I con- 
tinue to call them, that Duges proposed to classify the Acarina into 
families, solely by their varying natures and forms ; and this classifica-- 
tion held its ground for a long series of years, although it has been 
superseded in recent times. 
It is always interesting to watch the different developments of the 
same organ in allied creatures, and observe the various forms which 
it assumes, and the variety of uses to which it can be applied. Among 
the Acarina the palpi will be found to divide naturally into five great 
classes, viz. firstly, palpi which are almost obsolete, and have so 
greatly coalesced with the maxillary lip that they have almost ceased 
to be separate organs ; secondly, palpi of the insect-type ; thirdly, 
raptorial palpi ; fourthly, anchoring palpi ; and fifthly, antenniform 
palpi. The first, or anchylosed form of palpus is found almost entirely 
among the Sarcoptidae, or Itch-mites, and may not improbably be an 
instance of degradation from parasitism. The second, or insect-like 
form, is found in the Tyroglyphidae, Oribatidae, &c., and is always a 
small palpus having probably a tactile function ; it is kept bent 
towards the ground, and in constant up and down motion as the 
creature runs, swiftly and lightly touching the ground or whatever 
it is treading on, and apparently feeling the way or exploring for 
food ; it is quite possible also that these palpi may be endowed with 
the functions of smell or taste. The third class, the raptorial palpi, is 
that in which the most singular developments occur. Naturally, all 
the Acari that possess them are predatory ; but the converse is not 
true ; all predatory Acari are not possessed of them, for the great 
predatory family of the Gamasidae have palpi of the second type- ; and 
with them the mandibles are the seizing organs ; but the equally large 
predatory family of the Trombidiidae have the raptorial palpi as one 
of the principal features by which they are distinguished. This palpus 
