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PROCEEDINGS^ OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



iuul hhioed to the outer margitis of the apertures. In man}' forms 

 these apertures are very large and occupy the greater part of the 

 venter, in other and more highly organized species the openings are 

 much smaUor and quite remote from each other. 



The mouth-parts of the Oribatidne 

 are obscure. The palpi are very small, 

 tive-jointed, and arise from the labium. 

 They are usually in motion while the 

 mite is walking. The mandibles are 

 chelate in all save the genus Serrarlus. ' 

 The limbs of the cheht are commonly 

 toothed on the inner sides. In Seriu- 

 rlns the mandil)les are elongated and 

 rod-like, and there is no movable limb 

 at ti]); the sides are serrate, so that the 

 niandil)les act as a saw. The maxillie 

 have their basal joints united into one 

 transverse piece, the lal)ium, which 

 partly and sometimes wholly closes the 

 niouth-orilice. The maxilla? incline 

 •slightly toward each other; their tips 

 are broad and toothed. The Oril)atidte 

 deposit the eggs in crevices of wood, moss, fungi, or on the ground. 

 The six-legged larva remains for a few weeks in this stage, when, by 

 a molt, it becomes an eight-legged nymph. Tlie nymph passes through 

 three molts, increasing in size at each, the third molt bringing it to 



Fli.;. 12-1.— UaLUJINA IIUBBARDI. 



Fig. 125.— Oribatella armata. 



the adult condition. In some cases the eggs are not deposited, but 

 ripen in the body of the parent mite, the mother then dies and dries 

 up, her old shell remaining as a protection for the eggs till they hatch. 

 In some species the egg has a hard shell; the growth of the emln-yo 

 splits the shell and shows the pale vitelline membrane as a white band 

 around the ^gg. 



