HANSEX AND SÖRENSEN, THE TARTARIDES. 17 



wards. The lameliar »pouches» are directed horizontally 

 forwards from the bottom of the sac, but this occupying a 

 sloping position, their basal line is oblique when seen from 

 the side; the margins of the »pouches» at their origin from 

 the trunk are slightly more firmly chitinized than their walls. 



In Aranese the spirades (first pair) to the »lungs» are 

 shaped as a slit at the posterior margin of second abdominal 

 segment, but the front margin protrudes distinctly as a ridge 

 below the posterior one, so that the slit looks rather back- 

 wards. The spirade is proportionately longer than in Scor- 

 piones, wherefore the trunk expands rather little at the ex- 

 teriör side. A ]ongitudinal verticaJ section through abdomen 

 shows that the trunk is in the main as in Scorpiones, but 

 the triangle seen on the section is nearly right-angled, with 

 the right angle at the spirade; the posterior side is directed 

 upwards and only a little backwards, the lower side is much 

 shorter than in Scorpiones, but yet very distinct, while the 

 hypothenuse is the steeply sloping bottom of the trunk. The 

 structure looks rather as if the »pouches» originate from the 

 front wall of a flat sac, but this is not the case, which is 

 observed at a doser examination and from comparison with 

 the structure not only in Scorpiones just mentioned but espe- 

 cially in Tartarides (described in the sequel). The margins of 

 the »pouches» at their origin from the bottom of the trunk are 

 not, atleast not essentially, more firmly chitinized than their walls. 



Of Amblypygi Tarantula renifonnis (L.) Kraepelin has 

 been investigated. The structure resembles considerably that 

 in Araneae, but some noteworthy difference is observed. The 

 places of the four lungs are — in contradistinction to Oxo- 

 poei — easily seen from the outside, as of the sternites in 

 question the area beneath each »lung» is a little vaulted. 

 The posterior margin of the sternites is slightly or very 

 slightly emarginate at the spirade; seen on a vertical section 

 it protrudes backwards as a ridge. Proceeding from the 

 Araneae, one is inclined to consider this ridge as the front 

 (lower) boundary of the spirade, but a doser examination 

 and a comparison with the structure in Oxopoei shows that 

 an other interpretation ought to be preferred. The margin 

 of the ridge mentioned is the posterior end of a duplicature; 

 from this margin thin skin proceeds forwards above the poste- 

 rior part of the sternite. On a longitudinal vertical section 



Arkiv för Zoologi. Bd 2. N:o S. 2 



