56 ANIMAL PARASITES. 



some of them had turbid, purulent contents. The pustules were 

 very small or larger, so that they covered themselves with thick 

 scabs as large as a kreuzer. They also stood together in groups, 

 upon a common hardened base and exhibited fistulous passages 

 with pus, in which the Sarcoptes Bovis were found. Syringing 

 out the passages, evacuation of fhe matter, and mercurial oint- 

 ment led to a cure. 



The mite itself presents the following peculiarities. It is twice 

 as long as broad, pointed towards the head, rounded off at the 

 hinder part. The proboscis consists of two jointed superior valves, 

 directed straight forwards, of two central, spiniform, thin palpi, 

 and two inferior valves, curved in the manner of a retort, of which 

 the right one bears two long bristles. Hering has not seen this 

 mite. 



The eight feet are five-jointed, arranged in two groups. The 

 two anterior (pairs of) feet originate beneath and close to the 

 head towards the margins of the body ; the posterior feet behind 

 the middle of the belly. The first joint, attached to the belly, is 

 short ; the other four are tolerably equal ; and the last is fur- 

 nished with a sucking disc. Every foot bears two short hairs on 

 each joint, but the third joint of the first pair of feet has a 

 stronger and longer hair. The entire body exhibits a number of 

 stronger, uniformly distributed, bristles, springing from separate 

 warts or papillse ; on the abdomen there are twelve large ones, 

 without reckoning the smaller ones. (See Rubner's Illustrirt. 

 Zeitung, i, 5, 1852.) The figure of the cast skin of this mite 

 here given is omitted by me. 



5. The Sarcoptis Ovis (figs. 4 and 5), first correctly described 

 by Walz, is similar to the horse-mite, but smaller (0-16 O22'" 

 in length and 0'16 0'17'" in breadth), moderately hard; the 

 male is roundish, the female more oval. Each of the external 

 posterior feet has two long bristles ; the fourth pair of feet in the 

 male is rudimentary. The horny framework of the feet is red- 

 dish-brown. They bore passages beneath the epidermis, from 

 which the little hexapod brood, which grows quickly and becomes 

 octopod, issues in from about eleven to sixteen days. This mite 

 has been seen but rarely upon man ; Hertwig's experiments in 

 inoculation gave no results. 



Apparently very similar to the last-mentioned mite in struc- 

 ture is the species of Acarus found by Willigk in Favus crusts, 

 although it approaches the Dermanyssi in the want of bristles 



