836 CLASS V. AKACHNIDA. 



There is but one family 



Fam. 1. Cheliferidae with the characters of the Order. This includes 

 3 sub-families and 9 genera. 



Sub-fam. 1. Cheliferinae. A galea and no epistome, eyes 2 or none. 

 Two genera Chelifer (Fig. 548) and Chernes ; Chel. cancroides is foimd 

 in houses and sometimes termed the book-scorpion ; Chel. hermanni, 

 Chel. cancroides, Chel. meridianus, Chel. subruber, and Chel. latreillii 

 are British. Chernes is blind, whilst Chelifer has two eyes. Cher, 

 nodosus, Cher, insuetus, Cher, cimicoides. Cher, dubius, Cher, phalaratus 

 are all British. Sub-fam. 2. Garypinae. The cephalothorax is con- 

 tracted anteriorly, with 3 genera : Chiridium muscorum is British and like 

 Chel. cancroides lives in houses, Olpium, Garypus. Sub-fam. 3. Obisiinae. 

 Cephalothorax broad anteriorly, very large chelicerae. Obisium(Fig. 547) 

 of which the species O. muscorum. O. sylvaticum and 0. maritinum are 

 British ; Roncus with the British species P. cambridgii and R. lubricus ; 

 and Chthonius with Chth. orthodatylus, Chth. rayi, Chth. tetrachelatus and 

 Chth. tennis found in Great Britain. 



Order 7. PODOGONA (MERIDOGASTRA). 



Tergum of cephalothorax in two parts, the. anterior hinged and 

 hanging over the base of chelicerae ; no cephalothoracic sternal plates 

 visible ; abdomen apparently of four segments ; fifth pair of 

 appendages modified in the male as intromittent organ : spiracles 

 on thz cephalothorax. 



Tliis order has recently been established * for the reception 

 of the genera Cryptostemma and Cryptocellus. The squarish 

 tergum of the cephalothorax is divided into an anterior hinged 

 part, the " cucullus " which overhangs the mouth, and a larger 

 posterior portion. The sternum requires dissection to make it 

 evident. The abdomen consists of nine segments, but some of 

 these are so small and so masked that only four segments are 

 as a rule visible. The chelicerae are chelate and the pedipalps are 

 weakly so. The coxae of the first three pair of legs are immov- 

 ably fused, but those of the fourth and last pair are capable of 

 restricted movement. The terminal joints of the third leg in 

 the male are highly modified for depositing the semen. There 

 are no eyes. The single pair of spiracles are situate on the 

 cephalothorax above the coxae of the third legs. The genital 

 aperture is between the second and third sterna of the abdomen. 



* Lankester, Q. J. M. Sci.. xlviii. this contains a list of literature, but 

 see also the very important memoir of Hansen and Sorensen On Two Orders 

 of Arachnida, The University Press, Cambridge, 1904. 



