On a neio Type of Stridulating-organ. 401 



(10) Sciurus hocourti lylei, subsp. n. 



Size largest among the forms of hocourti. 



General colour above smoke-grey, individual hairs mouse- 

 grey basally, then white, a large proportion with black tips. 

 Face and head faintly washed with orange-rufous. Tail 

 basally (50 mm.) coloured like the back, then (50 mm.) white, 

 and finally bright cinnamon -rnfous. Hands and feet finely 

 grizzled black and white. Under surface a pale bright orange- 

 rufous. 



Dimensions of typo (taken in the flesh) : — 



Head and body 213 mm. ; tail 200 ; hind foot 49 ; ear 20. 



Skull : greatest length 51 (54) * ; basilar length 40 (43) ; 

 zygomatic breadth 30 (32) ; brain-case breadth 23*5 (24) ; 

 interorbital breadth 18 (20) ; nasals, length 14 (16*5), 

 breadth proximally 4, breadth distally 7; diastema 11*1 (12*6) • 

 upper molar series 10*3. 



Hah. Chiengmai on the Me Ping. 



Type. Adult female. B.M. no. 7. 11. 13. 11. Original 

 number 242. Taken by Mr. T. H. Lyle on 12th August, 

 1907, and presented by him to the Museum. 



Three specimens examined, all very like one another. The 

 complete absence of either red or brown in the coat (above), 

 the bright orange-rufous belly, the obsolescence of the red 

 colouring on the head, and the paler hands and feet make this 

 a very striking form among the subspecies of hocourti. 



XLV1IT. — On a new Type of Stridulating-organ in Mygalo- 

 rnorph Spiders, with the Description of a new Genus and 

 Species belonging to the Suborder. By A. S. HlRST. 



Several types of stridulating-organs are known to occur in 

 the spiders of the suborder Mygalomorphee. These organs 

 consist of arrangements of spines and bacillae, the structure 

 and disposition of which differ much in the groups and 

 genera in which they are present. In some of the groups of 

 the subfamily Aviculariinse (Thrigmopceese &c.) the apparatus 

 lies between the posterior surface of the mandible and the 

 anterior surface of the maxillipalp, and this is also the case 

 in some of the genera of the Dipluridae. In other groups of 



* The figures in brackets are those of a rather older individual. 



