ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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other species of Peripatus, Mr. Fletcher has denied the oviparity of 
P. LeucJcarti , and the solution of the difficulty will probably be found in 
the distinctness of the larger Victorian species from that of New South 
Wales. 
5. Arachnida. 
Researches on the Arachnida.* — M. P. Gaubert finds that the cuticle 
of Arachnids is made up of two and not of three layers, as Schimke- 
witsch asserts. The inner is formed of several superposed lamellae 
which are parallel and continuous over the whole extent of the skeleton. 
The rupture of the chitinous envelope at ecdysis depends on a purely 
mechanical action, due to the pressure caused by the increased volume 
of the animal. The elongated hypodermic cells found on the jaws are 
not, as Dahl thought, nervous, but are glandular. They secrete a 
viscous fluid which doubtless co-operates with the products of the 
maxillary glands and of the rostrum. The chitinogenous layer of the 
Phalangiidse has modifications similar to those of the Araneidse; some 
of the cells become glandular. A similar modification is seen in 
Galeodes and the Scorpions. The structure of the hairs is similar to that 
of the integument ; they are formed by a series of concentric layers, 
the outermost of which may be ornamented. The tendons which are 
inserted into the integument are internal products of the chitinogenous 
layer. The glands, too, are modifications of the same layer. The 
poison-glands are enveloped by a layer of muscular fibres ; they are not 
limited internally by the connective layer, as MacLeod states, and they 
have not the general sarcolemma described by Schimkewitsch. 
The following may be regarded as sense-organs belonging to the 
appendages ; the lyriform organs, the pectines of Scorpions, the coxal 
scales, and a new organ which the author has discovered at the extremi- 
ties of the first pair of limbs and of the palps of the Galeodidae. These 
last are formed of about fifty chitinous tubes, which put the interior of 
the limb in communication with the exterior. They are terminated 
internally by a hollow sphere, the diameter of which is three times that 
of the tube. The sphere is followed by another tube and then there 
comes a funnel, so that the whole has the form of a pendulum of a 
clock. All these tubes are imbedded in the chitinogenous layer 
which is here proportionately much thicker than it is in the rest of 
the body. Each funnel is provided with a nerve-fibre which is similar 
in structure to those found in the coxal scales. 
The mouth-parts of Arachnids have been found to exhibit many 
differences in the different orders; the author has studied not only the 
muscles which move them, but the pharyngeal plates of Spiders and the 
pieces which altogether resemble them in structure, but which are found 
on the lateral appendages. 
The musculature of the appendages is very uniform ; the tendons 
increase in number with the shortness of the muscle. The last joint of 
the limbs has no muscles, and its movements are consequently passive 
in all except the Acarina. Although the limbs of Arachnids have 
generally the same number of joints it is usually only the first two that 
are homologous. At each cardiac systole the blood is driven into the 
* Ann. Sci. Nat., xiii. (1892) pp. 31-184 (4 pis.). 
