NEW OR LITTLE-KNOWN AOARI. ^75 



Host : A skink (Ifabicia quinquestriata Licliteustein) ; numerous- 

 specimens collected by the author on this host at Khartoum 

 (Feb. 1923). 



LiPONYSsus SYLViAiUJM Can, & Fanz. 



Miss E. Kniglit, of the Lister Institute, has sent me a number 

 of specijnens of L. sylviarum found on hens at Bletsoe, Bedford- 

 shire. The mites occur round the vents of the birds, and seem to- 

 multiply very rapidly. They form colonies, and do not leave the 

 birds during the daytime, as is the habit of the common red 

 mite of fowls {Dermanyssus gallince Redi). The tail-featliers,, 

 particularly the fluffy portion near the base, become covered with 

 great numbers of mites. Later on, the parts of the skin attacked 

 by the mites become raw, and a hard scab appears afterwards. 

 Although previously founct on Pigeons in this country, this is the 

 first case of this mite becoming a pest of poultry here. In the 

 United States a number of cases of L. sylviarum attacking hens 

 are known, and it is regarded as a very injurious species, egg 

 production of the infested birds being greatly reduced. 



Dermanyssus (Allodermanyssus) sanguineus Hirst. 



This species was described from specimens found on liathts 

 rattus and other rodents in Egypt. It has also been recorded by 

 Ewing as occurring in the L^nited States (Proc. U.S. Nat. Mus. 

 1922, vol. 62, art. 13, p. 25). During February 1923, 1 collected 

 a number of specimens of this mite from Ratius alexandrinus^ 

 (grey-bellied form) and irom. Mus musculus gentilis at Khartoum, 

 Sudan. 



KiiiNONYssus (Nkonyssoides) nucifuagvE, sp. n. (Text-figs., 

 4 & 5.) 



5 . Two large dorsal shields are present, covering practically 

 the entire upper surface of the body instead of only a single 

 anterior dorsal shield as in most species of Rhinonyssus. 

 Apparently only one or tAvo paiis of exceedingly short and 

 inconspicuous hairs are visible on the dorsal shields ; there are,, 

 however, also some very minute and inconspicuous circles on the 

 shields ; these minute circles no doubt represent the sockets of 

 the hairs present in other forms. Hairs on venter also mostly 

 obsolete or absent ; when present they are exceedingly short and 

 inconspicuous. Sternal plate indistinct. There is a clear space^ 

 ventrally which probably represents the genito-ventral plate ; it 

 is wide and apparently rounded oft* posteriorly. Anal ^jZate 

 distinct and pear-shaped, bearing three very short hairs. 

 Peritreme very short. Coxa? without spines or hairs, only minute 

 circles being present. A few very short spinules occur on the 

 proximal segments of the legs, and some longer fine hairs on their 



