37 



LINCOLNSHIRE FRESHWATER MITES. 



G. F. GEORGE, M.R.C.S. 



Arrhenurus curtus, n.sp. This mite is one of Thor's subgenus 

 Afajoa/i/rns, and when living" is, in colour, similar to many 

 individuals of Arrhenurus caudatus (the type of that sub- 

 division), but is at once seen to differ in its general appearance, 

 the tail part being comparatively short, giving the whole mite a 

 stuggy appearance. The chitinous skin is well developed, and 

 the end of the tail has no downward processes or projections, 

 but the outer corners are slightly raised, forming small humps. 

 When placed in preservative solution it soon alters in colour. 

 Mr. Soar gives the length of the whole mite as 1.28 mm. The 

 palpi and legs are of the usual type, having the spur on the 

 fourth leg, the hairs on the end of which are wavy. The two 





figures represent the upper and under surfaces of the mite, the 

 legs and palpi being omitted. If these figures are compared 

 with others which have appeared from time to time in the 

 Naturalist, such as A. inembrauafor, March 1903, p. 83 ; 

 A. pyriformis, June 1903, p. 215 ; A. mantonensis, p. 216 of 

 the same number; and A. insperatus, January 1905, p. 25, 

 the great difference in general appearance will be very evident. 

 I have only met with a single example of this mite. 



Pionacercus. The species of Pionacercus appear to be rare 

 in this district, I have only been able to identify one, whilst 

 Mr. Soar in Science Gossip for March 1900, page 303, figures 

 and describes the hind legs of the males of three species ; 

 the hind legs of the males are very peculiar, and vary so 

 much anatomically from one another as to form very good 

 marks of identity for each species. Mr. Soar however does 

 not say a word about the females, whose legs are quite 



1906 February i. 



