ARTHROPOD A. 93 



The members of this order, confined to a single genus, are found 

 in the West Indies, South America, the Cape, Australia, and New 

 Zealand. Hutton says of the New-Zealand species that it is noc- 

 turnal, living in decayed wood and under stones, feeding " upon 

 animals," and able to shoot from its oral papillae a viscid fluid, 

 which hardens into a spider-like web, and by means of which it 

 catches its prey. It breeds all the year round, although in the 

 winter it is half-torpid. 



These animals have been classed with the Vermes ; but Moseley 

 has shown that they really belong to the Arthropoda, in which 

 they have also been placed by Schmarda, who has adopted Blain- 

 ville's earlier name of Malacopoda. 



Peripatidce. 

 Peripatus. 



Class III. ARACHNIDA. 



UNOGATA. ACERA. 



Head united to the thorax (cephalothorax) ; no antennas. 

 Abdomen not segmented, or if segmented not distinctly separated 

 from the cephalothorax, and never provided with limbs ; legs 

 never more than four pairs. 



The palpi, mandibles, and sometimes the anterior pair of legs 

 are variously modified ; the latter are, according to Claparede, 

 homologous with the labial palpi of insects ; the maxillary palpi 

 are known as " pedipalpi." All the appendages of the mouth 

 being posterior, there are no homologues of the antennae. The 

 eyes are simple and generally more than two. Respiration is 

 eifected either by pulmonary sacs or by tracheae, or by both, and 

 mure rarely by the skin alone. All Arachnida are digitigrade. 

 Like the Crustacea they have the power of reproducing lost 

 limbs. 



Arachnida " occur in the Mesozoic formations, while spiders 

 and scorpions of large size have been found in the Carboniferous 

 rocks." According to Schmarda there are about 4600 species. 



Solpugidea, Phalangidea, and Cheliferidea are sometimes 

 united to form the order Adelarthrosomata ; Phrynidea and 

 Scorpiodea form another order Pulmonaria, or they are all 

 united under the name of Arthrogastra, Araneidea and Acaridea 

 forming the Sphserogastra. Owen has also an order, Dermo- 

 physa, including Arctisca, Demodex, and Podosoniata, characte- 



