SCIENCE-GOSSIP. 



261 



as shown in fig. 2 A. On the fourth segment, count- 

 ing from the epimera, is a large stiff bristle of a 

 bayonet form. This peculiar feature renders identi- 

 fication easy. This spur is about 0.20 mm. in 

 length. 



Epimera. — Arranged in two groups. Pale yellow 

 in colour, same as other parts of body. 



Palpi. — Rather thick, about 0.24 mm. in length, 

 and without the pegs we' find in some other genera, 

 but they have a number of small hairs. 



Genital Area. — One broad platewhich reaches 

 nearly across the ventral surface of the body. It has 

 a number of small discs (fig. 1), about sixteen on each 

 side. 



Female. — I have not yet seen a female of this 

 species. 



Localities. — Found by Mr. Taverner near Oban, 

 N.B. Only one male specimen at present represents 

 this species in Britain. 



Acercus cassidiformis Haller, 1882. 



Male. — Body a long oval, being about 0.64 mm. 

 long, and 0.44 mm. in breadth. Yellow in colour, 

 with brown markings. 



Fig. 3. Acercus cassidiformis. Fourth leg of male. 



Legs. — Very similar to Acerais ligulifer, except 

 that it is without the spur on fourth segment. On the 

 tarsi are two strong bent spines (fig. 3), which are 

 very prominent, but are quite different in shape from 

 those on fig. 2. 



Epimera. — In the male appears to be all in one 

 group, the line down the centre being very fine. The 

 epimera also appears to be laid on another chitinous 

 plate, which covers the greater part of the ventral 

 surface and has a very granular appearance. This is 

 a peculiarity I have not noticed on any other water- 

 mite. 



Palpi. — Very like the palpi of the preceding 

 mite. Length about o. 24 mm. 



Genital Plates. — Are much closer to the 

 posterior margin of the last pair of epimera than 

 ■those of Acercus ligulifer. 



These plates are also let into the chitinous por- 

 tion I have just mentioned. They extend nearly 

 across the body, and have numerous discs on each 

 plate. 



Female.— A little larger than male, being 0.77 

 mm. long and 0.56 mm. in width. It has the first 

 and second pairs of tarsi larger and thicker than the 

 others, the same as the male. The epimera are 

 extended backwards to a point, and there are a 

 number of discs on each genital plate. The fourth 

 pair of legs are without the spur. At first sight it 

 may easily be mistaken for a female Curvipes. First 



pair of legs measure about 0.40 mm. The fourth 

 pair about 0.82 mm. 



Localities. — Found in 1898 in the Lake 

 District by Mr. Scourfield, and by Mr. Taverner at 

 Oban, N.B., in 1899. 



Acerais liliaceus Muller, 1781. 

 Male. — Body oval, rather more pointed on the 

 posterior margin than the two preceding species. 

 Length about 0.63 mm., width about 0.47 mm. 

 Colour a dirty yellow. . 



Fig. 



Acercus liliacetis. Fourth leg of male. 



Legs. — First leg about 0.63 mm. Fourth leg 

 about 0.79 mm. Colour same as body. The tarsi 

 of all the first three pairs of legs are thin and narrow, 

 not like those of A. ligulifer (fig. 1). The fourth 

 segment of the fourth pair of legs is also without 

 the spur. The tarsi of these legs are very singular 

 in form, having a number of stiff spines on the inner 

 curve. There are seven in a row at the posterior 

 end of the limb (fig. 4). 



Epimera. — Very similar to Acercus cassidiformis. 



Palpi. — About 0.30 mm. in length. 



Genital Area. — Composed of two plates which 



Fig. 5. Acercus liliaceus. Ventral surface of female. 



are placed close to the posterior margin of the 

 epimera. Like the others, they have a number of 

 discs on each plate. 



Female. — Fig. 5 shows the ventral surface of the 

 female with legs and palpi removed. Length about 

 0.72 mm., breadth about o. 52 mm. It will be noticed 

 how near it is in appearance to a female Curvipes. 

 The first leg measures about o. 56 mm. Fourth leg 

 about 1.04 mm. The tarsi are all thin and slim. 

 The palpi are about o. 30 mm. General colour same 

 as male— a dirty yellow with brown markings. 



Localities.— Found in 1898 in the Lake District 

 by Mr. Scourfield, and by Dr. George in Lincoln- 

 shire. 



Haller gives a figure and description of this mite 

 in his little book, but he calls it Fordia ahumberti. 



( To be continued.) 



