PARASITES OF ANIMALS. 



139 



garded as belonging to the Acarians, with the true mites. In 

 the adult state it inhabits the nostrils and frontal sinuses of 

 dogs and wolves, and more rarely, of horses and sheep. The 

 larvse, formerly described under tlie name of Pentastoma den- 

 ticulatum, lives in, cysts on the outside, or in the outer por- 

 tion, of the liver of sheep, deer, antelopes, peccary, porcu- 

 pine. Guinea-pig, rabbit, hare, rat, and cat ; and some- 

 times invades the human body in the same way. It has also 

 been found free in the visceral cavity of the body. 



In the mature state (Figure 84) the body is long, lance- 

 shaped, tapering behind, flattened below, and divided into 

 about ninety segments by transverse lines. The segments 

 next to the head bear two pairs of small, but strong and 

 Figure 84. sharp, retractile claws, which represent. the true 

 legs of ordinary mites. The mouth is broad- 

 oval, and provided with a hard chitinous lip. 

 The segments behind the head are perforated 

 by small openings, regarded by many as 

 spiracles, or breathing pores. The adult is 

 smooth, but the larvae are covered witli many 

 rows of small, sharp spines. The male is 

 only .07 to .08 of an inch in length, but 

 the female becomes three or four inches long, 

 and half an inch wide. The female genital 

 opening is in the tail, that of the male, in the 

 middle of the front part of the abdomen. They 

 are oviparous, and the young undergo a com- 

 plete and remarkable metamorphosis. 

 The adults live in the nasal cavities of dogs, and 

 produce an irritation of the delicate membranes, which 

 causes a flow of mucus, often accompanied by sneez- 

 ing. The eggs discharged with the mucus may ad- 

 here to vegetables or fruit, or get into drinking- 

 water, and in these ways gain admittance to the stomach of 

 man, or other animals. In the stomach they hatch into mi- 

 nute embryos, furnished with a boring apparatus and two pairs 

 of double claws. They bore their way through the intestines 

 and lodge in the liver or other parts, and soon become dor- 



