60 BRITISH TYKOGLYPHIP.E. 



Glycyphagus domesticus and G. spinipes it is as long as 

 all the other joints of the legs taken together. In the 

 third, or holding, leg of the heteromorphic male Ehizo- 

 glyphus the tarsus is very short, and comes to a point 

 at its distal end ; the whole joint being transformed 

 into a great clasping claw, which does not bear any 

 true claw like the other tarsi do. In Lentungula the 

 tarsi of the two anterior pairs of legs are similar to 

 that of the heteromorphic male of Rhizoglyphus, and 

 are used in climbing over rock, etc., but they bear a 

 distinct but small claw mounted upon a long flexible 

 peduncle which is capable of independent motion. 

 The tarsus of the fourth leg of the male Glycy- 

 phagus sciurinus, which must also be regarded as a 

 clasping leg, has a large blade along its dorsal sur- 

 face, which increases in width toward its distal end, 

 and projects beyond the body of the joint, and even 

 larger blades are to be found on the tarsi of the male 

 G. Crameri. Blades however are not common upon 

 the legs of Tyroglyphidse, although they are upon 

 those of the Oribatidse. 



In the genera Tyroglyphus, Rhizoglyphus, Garpo- 

 glyphus, and some other genera of TyroglyphidaB 

 the tarsi of the first or first and second pairs of legs 

 bear near their proximal ends, in the median line of 

 the dorsal surface, a curved rod of clear chitin some- 

 times increasing a little in diameter just at the distal 

 end, which is always rounded or truncated, never 

 pointed : the function, if any, of this rod is not known ; 

 but it is very persistent, appearing in a large number 

 of species and genera. The tarsi on the average bear 

 more spines and hairs than the other joints of the leg. 

 In Ehizoglyphus the spines are mostly very short and 

 strong, and the same thing may be seen on the tarsus 

 of Histiostoma rostro-serratwm. The spines are longer, 

 but not so strong on the tarsus of Hcricia Robini. 

 Sometimes one or more very long hairs are found on 

 the tarsus near the distal end, as in Carpoglypkus, 

 Histiostoma rostro-serratum, and the hypopus of Glycy- 



