ANNULOSA: ARACHNIDA. 22? 



abdomen, which is more or less distinctly segmented, but 

 generally exhibits no line of separation from the cephalothorax, 

 the two regions being of equal breadth and conjoined together. 

 The mouth is furnished with masticatory appendages, and 

 respiration is effected by tracheae, which open on the lower 

 surface of the body by two or four stigmata. 



Family i. Phalangidce. The well known "Harvest-spiders" 

 belong to this family. They are characterised by the great 

 length of the legs, and by the filiform maxillary palpi, termi- 

 nated by simple hooks. 



Family 2. Pseudoscorpionidcz (Cheliferida>). The "Book- 

 scorpion " ( Chelifer) is a common little animal in old books. 

 It is distinguished by the fact that the maxillary palpi are of 

 large size, and are converted into nipping claws, or chelae, thus 

 giving the animal the appearance of a Scorpion in miniature. 



Family 3. Solpugufa. In this family the abdomen is not 

 only very distinctly segmented, but is also clearly separated 

 from the abdomen. The mandibles in Galeodes, which is the 

 type of the group, are chelate, but the maxillary palpi consti- 

 tute long feet. 



DIVISION B. PULMONARIA. Respiration by pulmonary sacs 

 alone, or by pulmonary sacs conjoined with trachetz. Eyes six 

 or more in number. Abdomen usually distinct from the cepha- 

 lothorax. 



This division comprises the higher Arachnida, such as the 

 Scorpions, and the majority of what are commonly known as 

 Spiders; the former constituting the order of the Pedipalpi, 

 the latter that of the Araneida or Dimerosomata. 



ORDER I. PEDIPALPI. In this order are the true Scorpions, 

 together with certain other animals which are in some respects 

 intermediate between the Scorpions and the true Spiders. 

 The members of this order are distinguished by the fact that 

 the abdomen in all is distinctly segmented, but is not separated 

 from the cephalothorax by a well-marked constriction. They 

 agree in this character with the Adelarthrosomata ; hence the 

 two are sometimes united into a single order (Arthrogastrd), 

 but they are separated by the nature of the respiratory organs, 

 the latter breathing by tracheae, and not by pulmonary sacs. 



Family i. Scorpionidcz. The Scorpions are amongst the best 

 known of the Arachnida, as well as being amongst the largest. 

 They are distinguished by their long, distinctly segmented ab- 

 domen, terminating in a hooked claw (figs. 74, 76). This claw, 

 which is really a modified "telson," is the chief offensive weapon 

 of the Scorpion, and is perforated at its point by the duct of a 

 poison-gland which is situated at its base. The abdomen is 



