376 MR. STANLEY HIRST ON 



than in P. tarsaUs, resembling that of P. cestivus in this respect. 

 First tarsus produced beyond and. above the claw, but apparently 

 not so strongly as in P. tarsalis. 



Striated sensory (" olfactory ") hairs on first tarsus rather 

 similar to those of P. tarsalis ; they are four in number, all of 

 them being more or less club-shaped ; the one situated near the 

 distal end is very shoi^t and slender, the next is the largest, being 

 rather stout, close beside it there is another slender but not very 

 short sensory hair, the sensoiy hair nearest the proximal end of 

 the tarsus is very short and slender. Second tarsus with a short 

 but fairly stout sensory hair near the proximal end ; the claws of 

 this leg are distinctly bifid. 



There is an unusually stiflT bristle on the dorsal siirface of the 

 first leg (especially well developed in examples from Lyperosia 

 irritans (^ = Hcematohia serrata)). 



Length of body 205-225 yic ; width 110-140 /t. 



Habitat. Pseudoparasitic on Musca domestica (slides in collec- 

 tion of Laboratoire cle Parasitologie, Paris) and Stomoxys calcitrans 

 (the specimen from the latter was collected, by Dr. J. Burton 

 Cleland, and therefore is presumably Australian in origin). Also 

 numerous specimens (reddish in colour) found on an English 

 specimen of Lyperosia irritans. 



Prof. T. Harvey Johnston and M. J. Bancroft mention in their 

 paper on the life-histories of Musca austraUs (M. fergusoni) and 

 M. vetustissima (Proc. Roy. Soc. Queensland, 1920, xxxi. footnote 

 on p. 183) that "These flies may be parasitised by larval mites, 

 a red one probably Acarus muscarimi Linn., and also a minute 

 whitish species." The latter is probably the species identified as 

 P. a7nerica7ius in the present note. 



Pygmephorus americanus var. socotrensis, var. nov. 



$ . Very like the typical P. americanus in most respects, but 

 Avith the sensory (striated) setse on the tarsi of the first and second 

 legs difierent in shape, the largest one on the first tarsus being 

 considerably elongated and cylindrical, whereas in /', americanus 

 (typical form) it is club-shaped. The sensory seta of the penul- 

 timate segment of the second leg differs in a similar manner. 

 The paired oval structures situated near the front of the cephalo- 

 thorax are placed close together as in P. americanus, but are 

 constricted in the middle (perhaps difi'erences like this are merely 

 due to the presence of air or gas in the preparation). Pseudo- 

 stigmata globular as in P. americanus. There is a stiff dorsal 

 bristle on the second free segment of the first leg, much as in 

 P. ainericanus. 



Measitrements. Total length 210 /x ; Avidth 125 //.. 



Hah. Musca domestica : Socotra. A single specimen found on 

 a dry example of a fly from that locality. 



