339 



the siftiiigs oil a Hat dish ,suspeiuh_'(| over a hir^'e funnel, and 

 placing the funnel and all in the sunlight. The sunlight drives 

 the mites out of the siftings, and they fall through the funnel 

 into a vial below. 



The most convenient and satisfactory mounting media for 

 oribatids are Canada balsam and dammar balsam. Dissections 

 of the mouth-parts are frequently necessary. Material must 

 often be rendered partially transparent by means of potassic 

 hydrate or eau de Lalirraciue. 



In making the drawings 1 used an Alibr camera hicida. 

 The measurements were made with an ocular micrometer. 



External Anatomy. 



The body in the Orihufdlilcn (Fig. 1) consists of an anterior 



narrower region termed the 

 cephalothorax, and a posterior, 

 much larger, portion termed 

 the abdomen. The union of 

 these two regions is more in- 

 timate in some genera than in 

 others. There is usually an 

 evident di\ision l)etween the 

 cephalothorax and the ali- 

 domen except in the genera 

 Scii/iircrfc.r and Aiiimis. In 

 two genera, /Idji/ni/cnini ;ind 

 I'lilliirariinis, t li e cephalo- 

 thorax is hinged to the ab- 

 be folded down 



Ps.Ox 



Fk;. I. Diiiii.i IIS iiili'iis, dorsal view 



domen in such a way that the former can 

 against the ventral surface of the latter. 



The cephalothorax may be divided into 

 two parts; the rostrum (Fig. 1, h'n.) and _ 

 the posterior portion. 'I'he rostrum is the 

 anterior hood-like petition which protects 

 the mouth-parts. I'pon the rostrum is 

 found a pair of stout hairs termed rostral 

 /.''*. //.i; sometimes the 



Ml', a. 



hairs (Fig. 1. 



Fi( 



l5( SCg- 



Oiiliiifii hiiiik.t'i, iTian- 

 (iible. 



