230 



SCIENCE- G OS SIP. 



BRITISH FRESHWATER MITES. 



By C. F. George. M.E.C.S. 



ded from page iOo.j 



Arrenwms tabulator Miiller. 



-j- FOUND the male of this mite for the first time 

 JL on May 18th. 1900. It is strikingly different in 

 appearance from any other Arrenurus I have yet 

 observed. Its dark colour and the nearly parallel 

 sides of the tail, best seen when the under side of 



Fig. 1. A. iubuJator. Dorsal view. 



the mite is examined, at once distinguish it from 

 the other members of this family. As far as I 

 know, it had not been noticed since the time of 

 Koch, until Koenike figured it in the " Zoolo- 

 gischer Anzeiger." Piersig also gives two illustra- 

 tions on Taf. -40 of his great work. The figures 

 accompanying this article are drawn by Mr. Soar 

 from a living mite sent to him by me. After 

 drawing the dorsal and ventral aspects, he had the 

 misfortune to lose the little creature before he had 

 been able to make a side view. The general colour 

 of the mite, when alive, is a warm reddish-brown, 

 the caeca dark brown. At the outer edge of the 

 body there is a slight shade of green, more evident 

 after mounting in balsam. The impressed curved 

 line on the back is somewhat irregular, but very 

 evident from the sharpness of its edges and its 

 translucency. There are also eight circular, some- 

 what translucent spots, four in front and four 

 behind this line : they appear to be circular plates. 

 and seem to carry a minute and delicate tactile 

 hair. The eyes are bright crimson during life, but 

 become black after mounting in balsam. The tail 

 where it joins the body and for about the anterior 

 two-thirds is much thicker from above downwards 

 than the posterior third, forming a sort of ball, 

 notched at the posterior part, in the centre. The 

 lower third of the tail is somewhat translucent 



from its comparative thinness. The legs and palpi 

 are not green, bat a semi-transparent reddish-brown. 

 The fourth internode of the last pair of legs is 

 furnished with the spur so often found in male 

 specimens of Arrenwws. 



I have the satisfaction of knowing that this mite 

 is identical with the creature described and figured 

 by Koenike, this savant having kindly sent his 

 specimen to me for examination. He also informs 

 me he has examined the mite described by "Sig 

 Thor " as Arrenwrm medioratundata, and found it 

 to be the same creature. That this mite really is 

 Midler's A. tubulator is, perhaps, open to doubt. 

 Muller's figure is not very satisfactory, and his 

 description brief; besides, he says the legs are 

 green. Koch's figure is better than Muller's, but 

 he also says that the legs are green : moreover, he 

 speaks of two large back humps, which I have not 

 been able to discover. He further says that the 



^#fc 



Fig. 2. A. tubulator. Ventral view. 



mite is common in his neighbourhood. I trust 

 therefore that this matter will very shortly be 

 decided. 



Mr. Soar supplies the following measurements : 

 length about 1.10 mm., width about 0.70 mm. : 

 length of first pair of legs about 0.77 mm., length 

 of fourth pair of legs about 0.98 mm. 



Arrenurus maximus Piersig 1894. 



This large and very beautiful red mite was taken 

 at Enfield in June 1895. It is one of those wide- 



