Excerpta Zoologica : — Acarus folliculorum. 49 



Tetrarrhynchus inclosed in a distinct cyst beneath the peritoneal co- 

 vering of the intestinal canal of a young Testudo Mydas, which con- 

 firms the view that the Cestoidea and Cystica are not essentially di- 

 stinct, but can only be sections of the same family. Mayer calls this 

 worm Tetrarrhynchus cysticus. Dr. Peters, in a note to the memoir 

 in question, having compared it with Rudolphi's original specimen, 

 pronounces it to be identical with Tet. macrobothrias. 



Dr. Valentin (Mull. Arch. 1841, p. 435) found in the blood of 

 Salmo fario a number of microscopical Entozoa possessing lively 

 motions, effected by means of several variable appendages to one of 

 the sides. Gluge has detected more recently a similar animal in the 

 blood of a frog (ib. 1842, p. 140). 



Vogt (ib. 1842, p. 189. pi. x.) has published some contributions 

 to the history of the development of the Filaria. He found in the 

 blood of several frogs a number of small worms resembling Filaria. 

 In the same frogs were noticed in the ventral cavity several brown 

 fibrous cysts, which were however all empty. In several other frogs 

 were similar cysts filled with young Filaria, but in the blood none 

 of these animals could be detected. In another frog several large 

 Filaria, more than an inch in length, were situated in the ventral ca- 

 vity. In the female sexual parts of these, Vogt found embryos which 

 agreed in size and in form with the animals occurring in the blood. 

 From these observations he considers himself justified in drawing 

 the following conclusions : the young are deposited by the mother 

 in the ventral cavity, bore their way into the vessels, circulate for a 

 time with the blood, and are then deposited at suitable places for 

 their development, — the viscera. From the inflammation of the tissues 

 originate round about them fibrous cysts, in which they lie for a time, 

 and then penetrate into the ventral cavity, and the young there pro- 

 duced by them now commence the same course of life. 



AcARUS FOLLICULORUM. 



Simon has described in Miiller's Archiv, 1842, p. 278, an Acarus 

 which lives in the diseased and normal hair- sacs of man. He calls 

 the animal for the present Acarus folliculorum, from its occurring in 

 the so-called comedones, diseased hair-sacs (acne punctata), which are 

 frequent about the nose and mouth. It was noticed not only on 

 corpses, but also on several healthy persons. Of ten living persons 

 examined, it was found on three perfectly healthy and cleanly per- 

 sons. It is on an average T y long, and j T q'" broad, and occurs from 

 two to thirteen in each comedon. Its motions are sluggish, and rarely 

 for the purpose of changing its locality. The animal evidently be- 

 longs to the Acari ; the parts of the mouth consist of a snout, the 

 biarticulated palpi, and smaller bristle-shaped mandibles. The anterior 

 part of the body is provided with four pairs of feet, which are three- 

 jointed, and have three claws affixed to the last joint. Four distinct 

 forms have been observed, probably different stages of development 

 of the animal ; the first is characterized by the presence of three pairs 

 only of feet, while the other three forms have four pairs, and only 

 differ by the relative size of the abdomen. At times heart-shaped 

 bodies were met with, which Simon considers to be the eggs. 



Ann. $ Mag. N. Hist. Vol. x. E 



