42 



CENTIPEDES 



teen segments. There are a very large number of families in this 

 order which has a wide distribution in all the warm and temperate 

 countries of the world. Most of them are subterranean but a few 

 are found under stones and seaweed below tide marks. The 

 largest species, like the North African Orya harbarica^ measure 

 about six or seven inches in length, but most are only an inch or 

 two long. The writer has recently discovered a smaller species of 

 Orya, O. almohadensis, in central Tunisia which measures just over 

 two inches when extended and is scarcely longer than the com- 

 mon British Haplophilns subterraneus. 



Fig. 13. Poison claws of a centipede showing position of poison 

 glands and their ducts. 



The centipedes of the order Scolopendromorpha differ from 

 the Geophilomorpha in never having more than 23 pairs of legs, 

 while the segments of the antennae vary in number from 17 to 30. 

 The somites are not markedly divided and the tergal plate of the 

 basilar segment is fused with that of the first leg-bearing somite. 

 Spiracles are not found on every segment of the body. This order 

 is also widely distributed and includes two most important families, 

 the Scolopendridae and the Cryptopidae, of which the former con- 

 tains about 16 genera, including most of the large tropical and 

 sub-tropical species having 21 pairs of legs. The posterior pair of 



