E-GOSSIP. 



? 33 



BR] riSH FRESHWATER MITES. 

 B\ I ii mi i D. Soar, F.R.M.S. 



' page jh>). 



'■I \i S HYDRYl'HANTES KOCH, 

 r PHER] of diis genus recorded 



by v.irimis authors from different purls of the 

 Five arc described by Piersig from Germany, 

 bul ai present I can only record two from Britain, 

 I which arc fairly common, 

 The chief characteristics of this genus are: — Body 

 suit skinned. Legs well supplied with swimming 

 hairs. Claws to all feet. On the frontal portion of the 

 dorsal surface is a chitinous plate, which is very 

 conspicuous in all species. 



i. Hydryphantes ruber de Geer. 

 Female: Body oval. Length about 1.80 mm., 

 breadth 1.32 mm. Skin coarse ami granulated. 

 A number ol dermal glands are distributed over the 

 dorsal surface. Colour scarlet: in some cases very 

 (lark, in others very pale. ( In the anterior portion of 

 the dorsal surface is a chitinous pitch or plate, which 

 has the appearance of having been riveted to the 



Fig. 1. Hydryphantes ruber, Y Pors.il Surface. 

 skin of the body at each comer (fig. 1). On the 

 median line towards the front of this plate is a small, 

 dark spot that has the appearance of being a fifth 



PQ 



Fig. 2. H. ruber. Genital Plates. 



eye. This median eye is also found in one or two 

 species of Thyas, so it is not peculiar to this genus. 

 This plate is thick and granulated, and forms one ot 

 the principal points of identification in the soecies of 



the genus. Tl intoui ol this plate varies a little in 



ll specimens of this species. I have four 

 specimens before me, all varying a little, but not 



enough recogniti loubtful. The eyes 



on each side of this dorsal | ll on the 



margin of the body, and are halved in a 

 manner, giving a distincl paii each. The 



small, prominent, and very dark. 



Legs.— First pair about 1. 28 mm. Fourth pair 

 about 2.0 mm. Same colour as body, very strong 

 and very hairy (tig. I). All the feet have claws. 

 There is no difference in the leg structure in male, or 

 females, as in some of the genera before noticed. 



EPIMERA. — In four group distinct and 



very hairy. 



Palpi. -About 0.52mm. Fourth segment longest 

 It has no peg on the second segment, or fourth, but 

 iln- lirsi three segments have a number of pectinated 

 hairs. 



Genitai Area.— Composed of two plates. At 

 each end of each plate is a conspicuous disc. There- 

 are also two others (see fig. 2) partly covered with 

 the plates, which in some cases cannot be seen at all, 

 being wholly covered. In others, the plates are so 

 open that the whole of the disc is exposed. 



Locai.itiks. — Fairly common in England. 1 >r. 

 George has found it in Lincolnshire. I have taken 

 specimens at. several places around London, and Mr. 

 Taverner reports it in Scotland. 



2. Hydryphantes dispar Schaub. 



This mite can easily be recognised from the pre- 

 ceding species by the dorsal plate (fig. 5 . In all 



FlO. .;. //. dispar. Dorsal Plates. 



other respects it is similar to H. ruber, even in its 

 measurements. I do not think any further descrip- 

 tion necessary. 



LOCALITIES. — It is very common. I took large 

 numbers at different places in England in 1S97. Mr. 

 Taverner this year sent me some from Scotland. 



GENUS SrERCHON KRAMER. 

 This is another genus that contains several species 

 abroad, but at present I have only two to record for 

 Britain. One of these jis very common, and the other 

 is very rare. 



