ON SOME RARE ARACHNIDS 42 1 



reaches the dorsum, where its superior border is seen to form 

 a distinct chitinous ridge at the anterior part of the abdomen 

 in front of the dorsal scutum. Behind it terminates in a 

 concave border, forming the anterior lip of the rima genitalis. 

 At each side of this posterior border is the opening of one of 

 the anterior spiracles which lead into the pulmonary sacs. 

 This scutum is of a reddish brown colour. 



The VENTRAL SCUTUM fornis the posterior lip of the rima 

 genitalis. It is somewhat kidney-shaped, being shghtly 

 concave in front. The central part, corresponding with the 

 hilum of the kidney, is naked and of a shining grey colour. 

 It is semilunar in shape, and shows a short median groove 

 running towards the rima in the long axis of the spider's body. 

 It bears no hairs. The rest of the scutum is of a reddish brown 

 colour, and bears numerous hairs, these forming a regular 

 fringe round the central naked part. On the lower surface of 

 the abdomen in the middle line, and behind the posterior edge 

 of the ventral scutum, a dark convoluted duct is seen through 

 the integuments. This runs forward, and can be traced 

 behind the scutum to the posterior border of the central naked 

 part, where it disappears. Probably this is the oviduct, but 

 it is in quite a different position from the somewhat similar 

 structure seen in /. velox. 



The posterior spiracles pierce the ventral scutum near its 

 anterior border, and at some distance from the middle line. 

 Each is oval, and is placed slightly nearer the middle line 

 than the corresponding anterior spiracle. The apertures seem 

 absolutely independent, and there is no groove or ridge or 

 band of modified chitin connecting them. I regret that I have 

 not had a spare specimen which I could eviscerate and treat 

 with liquor potassse in order to study the arrangement of the 

 tracheae. 



At the posterior end of the ventral surface of the abdomen 

 Es a small narrow curved plate. This is known as the infra- 

 mammillary scutum. It is not well developed in the present 

 genus. 



