364 



SCIENCE-GOSSIP. 



yellow T-shaped patch in the centre. Eyes are small, 

 and wide apart near margin of body ; they are of a 

 bright red colour. 



Legs. — First pair about 2.64 mm. in length. 

 Second pair, 3. 54 mm. Third pair, 2.44 mm. Fourth 

 pair, 3.28 mm. In colour they are chiefly of the 

 same pale yellow as the body colour, but I took a 

 number of specimens in North Wales in 1896 which 

 had all the chitinous parts of a deep slaty-blue. The 

 first pair of legs are fitted with the long sword-like 



Fig. 2. A tax crassipcs. 

 Genital plate of female. 



Fig. 3. A tax crassipes. 

 Genital plate of male. 



spines which are peculiar to this genus ; they are 

 very strong, and movable at the base where joined to 

 the leg. 



Epimera. — In four groups (fig. I); the posterior 

 pairs are very large. 



Palpi. — About i.o mm. in length, being very long 

 in proportion to the body. The last segment but 

 one has three very strong pegs on the inner curve. 



Genital Area. — Composed of four plates on the 

 extreme posterior margin ; each plate holds three 

 discs (fig. 2). 



Male. — Very much like the female in structure. 

 Length 0.92 mm. It also has the two papillae on 

 the posterior margin in the same position as the 

 female ; and the long second pair of legs, which 

 measure 3.40 mm. The great difference is in the 

 genital area ; here there are only two plates (fig. 3), 



\0 V^l 



showing the differences in mm. will be of great 

 assistance in identification. 

 Atax crassipes : 



Fig. 4. A. crassipcs. Posterior margin of nymph. 



each plate holding six discs in the position shown in 

 drawing. 



Nymph. — Has all the structure of the imago, 

 except that it has only two pairs of discs on the 

 posterior margin (fig. 4). 



In Britain we have two distinct varieties of Atax 

 crassipcs, both having the same specific character- 

 istics ; but they differ so much in size that to distin- 

 guish one from the other I have named the large 

 variety major and the smaller minor. In var. minor 

 the palpi and legs are shorter in proportion to the 

 length of body than we find in var. major; but as 

 they appear to be fairly constant, I think a table 





Var. Major. 



Var. Minor. 





9 $ 



9 



3 



Length of body 



. 1.20 .. 0.92 . 



1.0 



. 0.7 



,, istleg . 



. 2.64 .. 2.42 . 



. 1.40 . 



. l.IO 



„ 2nd leg . 



■ 3-54 •• 3-40 • 



. 2.84 . 



. 2.50 



„ 3rd leg . 



. 2.44 .. 2.40 . 



. 1.36 . 



. l.IO 



„ +th leg . 



. 3.28 .. 3-04 • 



. 1.72 . 



. 1.50 



palpi 



. 1.0 .. 0.72 . 



. 0.36 



■ , "^^ 30 



The above are mean measurements, taken from a 

 number of specimens. 



Localities. — Very common everywhere. I have 

 taken large numbers from the Norfolk Broads, ponds 

 in Epping Forest, Suffolk, and North Wales. 



2. Atax taverneri Soar, 1899. 



Female. — Body about 1.12 mm. long, breadth 

 about 0.78 mm. Colour a pale straw -yellow. Very 

 similar in structure to the preceding species, and it 



Fig. 5. A, taverneri. Ventral surface of male. 



may easily be mistaken at first sight for Atax crassipcs. 

 It has the two papillae on the posterior margin in 

 the same position (see fig. 5). 



Legs First pair, 1.44 mm. Second pair about 



1.80 mm. Third pair, 1.40 mm. Fourth pair, 

 1.88 mm. The second pair are in this species longe 



Fig. 6. A . taverneri. Genital area of female. 



than the third ; but the fourth are the longest. The 



first pair have the sword-like spines, as in A. crassipcs. 



Epimera. — In four groups, but a hard chitinou 



Fig. 7. A, taverneri. Genital area oS miile. 



ridge runs down from the first pair of epimera to the 

 third (fig. 5). 



