235 



which is by no means the case in X. bifasciatus cf> though it is 

 so in a nearly allied species, Thom. erraticus Blackvv. 1834 '), which 

 in size and colour exactly agrees with Koch's description of his X. 

 bifasciatus cf. I have met with specimens of X. erraticus cf in the 

 neighbourhoods of Stockholm and Goteborg, and a cf ad. has been 

 kindly sent me from England by Cambridge. By Westring the male 

 has been confounded with X. ulmi cf (on which see farther on). 

 The length of the cephalothorax in X. erraticus Blackw. cf is only 

 2 millim., the length of the patella + tibia 3 millim. The bulbus 

 of the palpi has on the under side a strong, pointed spine curved 

 and directed inwards and somewhat forwards; outside and somewhat 

 in advance of this appears a much smaller and weaker, more blunt 

 spine, which is directed and slightly curved obliquely inwards. Both 

 these spines are curved in nearly the same direction, not towards each 

 other (as may be seen from Koch's figure, where however these spi- 

 nes are erroneously directed backwards instead of inwards). The 

 lamina bulbi has on its outer edge, just in front of the point of the 

 lateral process of the pars tibialis, a small knoblike process. The 

 said process of the pars tibialis is very short (scarcely reaching '/ 4 

 of the lamina's length) and strong: the process on the under side 

 of that joint is longer than it is broad, somewhat narrower in the 

 middle, slightly curved forward at the apex, so that the posterior 

 angle is almost a right angle, the anterior elongated and acute; the 

 apex itself is truncated , with a small incision near the posterior angle. 

 The female of X. erraticus is not with certainty known to me; I sup- 

 pose however, that a couple of small (dried) females in my cabinet, 

 which I had formerly referred to X. bifasciatus, belong to X. erra- 

 ticus; they are in fact not larger than X. cristatus, and of a yellow- 

 ish or pale brownish colour; the legs are without spots, the cepha- 

 lothorax has two parallel dark bands, and dark edges; the dorsal 

 band of the abdomen is indistinct: the upper side of the abdomen 

 has in front two blackish lines diverging backwards , and two blackish 

 points or small dots in the middle. 



(Pag. 417). 3. Th. bivittatus [= Xysticns ulmi (Hahn) 1831]. 

 As regards this species vid. infr. under Th. ulmi Westr. 



l) Researches in Zool. p. 408; — Spid. of Gr. Brit., I, p. 71, PL IV, 

 fig. 40. 



