8 Arachn. 
ARACHNIDA. 
giatct could distinguish odours. The Atlidce were very sensitive to 
odours, the Thomisidce but little so. By means of the sensory organs on 
the palps and limbs Spiders discover the presence and position of an 
insect in the web. 
Plateau (75) states that in female Arachnida the palpi are apparently 
of but little importance, their removal hindering neither the seizure of 
prey nor the spinning of webs. 
Michael (68) states that the supra-anal papilla in the female Glyci- 
phagus is the bursa copulatrix. MIsgnin (66) comes to the same con- 
clusion. 
Haller (33) has notes upon Cytochilus sarcoptoides and upon Tetra- 
nychus molestissimus of the Argentine Republic. A species allied to the 
latter appears to be the cause of the Port Natal Sicht , and possibly of 
the Erythema autumnale which obtains in the South of France. 
M^gnin (66) accounts for the sudden appearance of myriads of Mites 
by the following fact : During starvation all the organs of a young 
Glyciphagus become transformed into a gelatinous mass, which collects 
in the cavity of the thorax and becomes surrounded by a chitinous 
envelope. In this condition, entirely at the mercy of the winds, the 
creature remains until brought into an environment favourable for 
development. 
On the suicide of the Scorpion, see Baer (5) ; and for observations 
upon the effect of Scorpion stings upon human beings, see Thompson (93). 
Classification. 
Schimkevjtch (79) compares the Arachnida with the Insecta. The 
antennse of the latter are not represented in the former, but the post- 
oral appendages in the two groups correspond, pair for pair. With 
regard to the Pycnogonida and Arachnida , the four pairs of legs in each 
group are supposed to be homologous ; the mandibles answer to the 
chelicerae, and the palps and oviferous legs together to the maxillae. The 
larva of the A carina is compared with that of the Chilognatha . The 
Crustacean character of Limulus is maintained.. 
Oudemans (73) looks upon the Acaroulea as a special group, which 
should be separated from the Arachnoidea . The Tardigrada are allied 
to the Chcetopoda more nearly than to the Arachnida. 
Thorell (91) criticises the classification of the Araneidea propounded 
by Dr. Bertkau. For a discussion concerning the claims of two natural- 
ists for priority in formulating a particular classification of the A rach- 
nida , see Lankester (59, 60), Claus (23, 24), and Bertkau (9). For 
the anatomy and classification of the Phytoptidce y see Nalepa (71). 
Habits, Mimicry, &c. 
The Attidce , Bertkau (11) states, frequently resemble Ants ; so also 
do the Drassidce , and particularly the genera Phrurolithus and Micaria. 
Among the Thomisidce and Epeiridce this kind of mimicry is unknown ; 
but the Theridiidce furnish a beautiful example in Formicina mutinensis . 
