SCIENCE- G OSSII\ 



45 



He also figures another species, T. stolli, described 

 by Koenike. 



The two great characteristics of Thy as are, first, 

 the absence of swimming hairs, and, secondly, the 

 presence of a thoracic, or third impaired median 

 eye, or stigma. 



1. Thyas venusta Koch. 



Body. — Soft, in shape oval, but truncated in 

 front, and flattened on the back, on which are 



Fig. 1. Thyas venusta. Female. Dorsal surface. 



dimples arranged in rows. Length of female, 

 1-68 mm.; breadth, 1-28 mm.; palp, 0-48 mm.; 

 first leg, 1-28 mm ; fourth leg, 2 - mm. ; length of 

 genital plates, about 0-33 mm. Skin finely granu- 

 lated. 



Epimera in four pairs. 



Fig. 2. Thyas venusta. Female. Yentral surface. 



Legs weak in proportion to the size of the body 

 and without swimming hairs. 



Fig. 3. Female. Right Fig. 4. Female, 



palpus under side. Genital plates. 



Thyas venusta. 



Palpi and genital plates resembling those 

 of Hydryjihantes. 



Eyes.— On the front border of the truncated 



body are placed the two double or helved eyes, one 

 on each side of the median line and wide apart ; 

 the single or impaired median eye is placed behind, 

 forming the apex of a triangle and surrounded by 

 a raised ring of chitin. 



Colour. — Vermilion, with paler legs. 



In my neighbourhood this mite is rare, as I have 

 only found one, a female specimen. This was last 

 year. Mr. Soar has been more fortunate : he 

 obtained them in March, 1896, at Chingford, in the 

 Cuckoo Ponds, also at Christchurch in Hampshire. 



2. Thyas extendens, nov. sp. 



- In Science-Gossip for October 1900, pp. 132- 

 133, is a paper written by Messrs. Harris & Soar. 

 The latter gentleman describes and figures a new 



Fig. 5. Thyas extendens. Showing projection of mouth organs. 



species of Thyas, which I propose to call extendens 

 from the fact observed during life, and well shown 

 in the mounted specimen kindly lent to me by Mr. 

 Soar, of its extending the palpi and mandibles- 

 (fig. 5). 



In figure this mite differs from T. venusta in 

 being more pyriform. 



Colour of the body is bright scarlet, and the legs 

 of a straw yellow. 



Eyes. — The median eye is not very conspicuous, 

 but surrounded by a chitinous ring, as in T. venusta. 



Female. — Length, 1-50 mm. ; breadth, 1T0 mm. 

 First leg, length, 0-88 mm. Second leg, 0-96 mm. 

 Third leg, 1-0 mm. Fourth leg, 1-36 mm. 



Palpi.— 0-32. Mouth organs project 0-25 mm. 

 beyond the body. 



Localities.— The New Forest, Hampshire, April 

 14th, 1900. 



3. Tltyas longirostris Piersig 1895. 

 This mite was found in Ireland by Mr. Halbert 

 in 1899. I have examined Mr. Soar's mounted 



