6o8 



IV AR TRAGARDH 



There is, in my opinion, only one way in which to account for this highly 

 aberrant number of hairs in Sejus viz. to assume, that in this genus the epi- 

 gynial shield is not homologuous to the epigynial shield of other Mesostigmata 

 but consists of this shield fused with elements of a ventral shield which has 

 the supernumerary hairs. There is, however, a serious obstacle to this theory, 

 viz. that the lateral sides of the epigynial shield project as free blades and 

 cover the base of coxae III and IV. 



Of the sternal hairs one pair is inserted in front of the middle of coxae 

 II and as far from the anterior as from the lateral side, one pair is inserted 

 on a pair of small, rounded, faintly discernible shields near the median line and 



in front of a faint semicircular suture, 

 which is the anterior border of a 

 transversal shield which forms the 

 anterior lip of the genital aperture 

 and which bears two pairs of hairs. 

 The genital aperture is situated 

 far forwards, in front of the posterior 

 margin of coxse II and is shaped as 

 a narrow fissure, curved in an even 

 curve backwards. The genital shield 

 is much longer than in S. togatus, 

 with convex sides and truncated at 

 the posterior end on a level with the 

 hind margin of coxae IV. Of the 3 

 pairs of hairs^ one is inserted on a 

 level with the middle of coxae III, 

 one in the angle between coxje III 

 and IV and the last pair near the 

 anterior margin of coxa IV. 



The peritrematic and parapodial 

 shields are fused, but the metapodial 

 shields are free and triangular, with 

 rounded sides and angles except the 

 anterior one which is sharp (fig. 118). 

 arge, with well rounded posterior margin and almost 



Between the shields there 



118. 



Figs. 118 — 120. Sejus insulanus n. sp. 

 Left half of ventral side. 119. Sternal and 

 genital shields 



120. Mandible. 



Ventri-anal shield 

 straight anterior margin, and granulated surface 

 are projections of the same shape as the marginal ones, carrying curved hairs. 



The legs are short and stout, richely provided with projections bearing 

 hairs, similar to the marginal ones. 



Mouthparts (fig. 120); of these I have only been able to examine the 

 mandibles. The lower jaw is slender, only slightly curved, with short terminal 

 tooth and further backwards a small tooth. The upper jaw is more than twice 

 as big as the lower one, with sharp terminal tooth, the cutting edge with two 

 small teeth and further backwards a dense row of very small teeth. 



' Owing to the bad state of preservation of the single specimen I have not been able to 

 ascertain the presence of the 4th pair of hairs present in 6". togatus (comp. TrAgArdh 191 2, 

 fig. 29). 



