510 . ARACHNIDA. 



by a small valve-like flap, the genital operculurn] ; on the second 

 abdominal segment are attached two peculiar comb-shaped structures, 

 known as pectines. The latter are probably the remains of the appen- 

 dages of the segment, and serve as tactile organs. The males are 

 distinguished from the females by their broader chela? and longer 

 post-abdomen. 



The females are viviparous. The development of the ovum takes 

 place in the ovary, and the embryos have the rudiments of appendages 

 on the pne-abdorneii (fig. 411). 



The Scorpions live in warm countries, and leave their hiding-places 

 at dusk. AVhen they run, the post-abdomen is bent upwards over 

 the back. They seize their prey, i.e., principally spiders and large 

 insects, with their large chelate pedipalps, and sting them to death 

 with their caudal poison-spine. Some species attain a very consider- 

 able size, and their sting may even prove fatal to man. 



Fam. Scorpionidae. iScnrj>ii> ntropfpiix Schr., 

 of small size and with only six eyes, in Italy. 

 Androctonus ocnitaitiix Am., Bittlmx ttfer L. 



Order 7. PSEUDOSCORPIONIDEA.* 



Arachnida of small size and resembling 

 scorpions, but without caudal spine or 

 poison gland. They breathe by means of 

 trachece. 



The Pseudoscorpions are far smaller and 



FIG, 412. Ooisium tromoMioides 



(r^rjne animal). A7, Pedi- more simply organised than the scorpions. 



palpus ' They bear much the same relation to the 



true scorpions that the mites do to the spiders. In their form and 

 the structure of their cheliceras and chelate pedipalpi they resemble 

 the scorpions. On the other hand, the hind end of the segmented 

 abdomen does not become narrow so as to form a post-abdomen, 

 and is without a caudal spine and poison gland (fig. 412). They 

 all possess spinning glands, the openings of which lie near the 

 genital openings on the second abdominal ring. They possess only 

 two or four ocelli, and respire by means of trachea?, which open by 

 two pairs of stigmata .on the two first abdominal rings. They live 

 beneath the bark of trees, in moss, between the leaves of old books, 



* W. E. Leach, On the characters of Scorpionidea with description of the 

 British species of Chelifer and Obisiura,'' Znul. Misci'U. III. A. Meuge. Ueber 

 die Scheerenspinnen,'" J\'ntfxfr Scliriftrn <1<T naturforxeJi. Gesellsclia-ft zw Danzig 

 V.. 1855. I,. Koch. " Uebersichtliche Darstellung cler europ. Chernetiden," 

 Nuraberg, 1873. 



