S68 mi. JOHNSTON ON THE ACARIDES OF BERWICKSHIRE. 



Lc^s 8 feliorter than the body, 6-jointed, armed with short 

 sj lines, ta])ering to the tarsus which is terminated jvith an 

 obversely conoid elongated vesicle ; the two anterior are remo- 

 ved at the origins from the two posterior jjairs and stouter, 1st 

 pair rather thicker than the 2d but equal in length, 3d pair 

 shortest, 4th rather the longest and slenderer ; the 2d and Sd 

 joints of the first and second pairs are swollen, and the 2d 

 joint of the first is armed with two stout and longer bristles 

 projecting from the inner side : Venter brown, even and 

 smooth, the anal pore posterior and submarginal in the centre 

 of a small heartshaped elevated region : /^l;m very delicately 

 striolate on the hinder parts at least : Bristles from a bulbous 

 root, straight, setaceous, smooth ; those on the posterior 

 membranous margin of the body numerous and longest ; those 

 of the legs shorter than the diameter of the joint, excepting 

 those on the hinder legs which are rather longer. 



The specimens from which this description is derived were 

 taken from a long-tailed field mouse, caught by Mr. Broderick 

 in his house at Belford, in the winter of 1848. "I have 

 caught," says Mr. Broderick, " in the same trap, set in the 

 same place, several common house mice, but did not find any 

 of the Acari upon them." The mite is small, and about the 

 size of Uropoda vegetans. It runs quickly ; and, when at 

 rest, the palpi and posterior legs are held bent under the ab- 

 domen, while the mandibles are thrust far beyond the palpi. 

 It belongs to the family Gamasides. In the structure of the 

 oral organs there is a close resemblance to Eumseus, but there 

 is a considerable difference in the character of the legs. 

 These remind one of those of the true A earns, and, in their 

 form and origin, entirely correspond with the typical species 

 of Lajlaps of Koch, to which genus I have accordingly re- 

 ferred it. 



The little tubercles on the back, in some lights, resemble 

 punctures. They are, perhaps, connected with the bristles, 

 and may be their bulbous roots. 



25. Uropoda cassidea. 



U. ovale-orbiculata brunnea nitida setis rectis aspersa, 

 pedibus anticis setigeris, posticis brevioribus solumque spi- 

 nosis. — Uropoda cassidea, Gertais in Walck. Insect. Apt. iii. 

 221. 



