58 



ANIMAL PARASITES. 



Fig. 6. 



marking, which rather disappears as the parasite imbibes. 

 Scattered hairs are to be seen springing from pores or little 

 warts (fig. 6). 



The two posterior pairs of feet spring from the belly close to 



each other. Each foot is 0-089 

 0-(T97 mill, in length, and presents 

 five joints, the shortest of which is 

 the coxa ; the strongest piece, 

 which is slightly bowed out late- 

 rally, and 0*018 mill, in length, 

 represents the femur, which is fol- 

 lowed by tibiae, 0-015 in length, 

 and a very long, conical terminal 

 joint (tarsus) with a stem and 

 sucking disc. 



The organ of manducation con- 

 sists of two pairs of nipper-like 

 chitinous structures, finely denti- 

 culated anteriorly and interiorly, 

 and united behind into a ring, so 

 that an articulation between the 

 individual lamella of the biting 

 nippers could not be discovered. Near the biting nippers originates 

 a three-jointed antenna, and ch>se to and between the anterior feet 

 some bristle-like hairs. The anus is situated on the abdomen, and 

 on each side of it two strong hairs. Numerous roundish or oval 

 eggs ; 0-025 0*169 mill, in length, filled with brownish granules 

 (yelk), and long, burst egg-shells were also found. These mites are 

 certainly supplementary to the Favus. Moreover, Hermann has 

 already described an Acarus favorum. " Mite ovale, convexe, 

 pdle, couverte de soies, 4 sur le derriere du dos, dressees en 

 haul et etalees" Hering compares it with the species of 

 Sarcoptes mentioned under 3 b. 



We have still to refer here to a similar occurrence, namely, 

 that of the mites in a case of plica polonica. Hessling narrates 

 (Rubner's ' Illustrirti Med. Zeitung/ i, p. 5, 1852), that, together 

 with innumerable lice, he accidentally found some mites not pecu- 

 liarly belonging to the disease. I pass over the first form entirely, 

 because it is much too imperfectly described, as Hessling only 

 found fragments of it, which appear to me to look very little like 

 a mite. 



