TRÄGÄROH, ARACHNOIDiE. 39 



Farn, rarasitidao. 



Subfain. Uropodince. 

 Uropoila Latr. 



Urdltodii plana n. sp. 

 (PI. 2, fig. 6. PI. 3, figs. 8, 11, 14—10, 21, 22 & 28.) 



Deiitonymjiha. 



Average length 0,i)2 mm. Greatest width 0,7o mm. Colour straw-yellow. Tex- 

 tur e finoly punctured. The shape of tlie body is broad oval, anteriorly falling off 

 a little more than posteriorly, wliere it is nearly semicircular. 



The dorsal side is protected by a single shield, which Covers the whole siir- 

 face. The dorsal shield bears at the front margin the socalled vertex, which is very 

 narrow and shaped like that of U. 'paiavina Can. The vertex (PI. 3, fig. 16) is 

 completely fused with the dorsal shield on the dorsal side. Its anterior edge has 

 a median, rounded, rather deep incision and is slightly excavated on each side of the 

 incision: outside the excavations the edge thiokens gradually to a ridge, Avith rough, 

 granulated surface. The dorsal surface of the vertex exhibits laterally 5 — 8 pairs of 

 narrow, rachating ridges and is very finely punctured. There is only one pair of hairs; 

 they are large, but weak, inserted in deep pores on both sides ot the median incision, 

 and curved outwards and obliquely backwards. On the ventral side the posterior 

 limit of the vertex is discernible as a transverse line. 



The dorsal shield (PL 3, fig. 21) bears hairs of two different kinds. Round 

 the margin, but inserted on the ventral side of it, is a closely set row of Aveak, 

 pointed and flat hairs, which curve upwards round the margin and afterwards cen- 

 tripetally as nearly to rest on the dorsal shield (PI. 3, fig. 28). There are 56 — 58 

 pairs of them. The other hairs are arranged chiefly in three nearly concent- 

 rical rings. 



In the outer ring there are 15 pairs of hairs; the hairs which lay close to the 

 surface are directed outwards and exactly of the length to reach the margin. At 

 the anterior side of each hair, except of the anterior one, there is a pore, which 

 communicates through a narrow tube with a sphserical gland measuring 0,09 mm. in 

 diameter. The median ring consist of 12 pairs of hairs, somewhat smaller than those 

 of the outer ring and directed centripetally upwards. The pores in which they are 

 inserted are connected, one with another by irregulär depressed areas of the cuticle, 

 which thus form on irregulär oval and wavy ring, a little nearer to the margin than 

 to the centre of the shield. The ring is open at the back and in the front, where 

 there are three pairs of hairs in the space between the outer and the median row. 

 The inner ring consists of 7 pairs of hairs, the pores of which are flanked by markings 

 of the cuticle, similar to those of the median ring, and besides exhibit a pore each, 



