SARCOPTID^ 379 



This species has been described by Trouessart, who found 

 numerous specimens, some adult, others in the developmental stage 

 (larvae, nymphs), and ova, in the fluid removed by puncture from 

 a cyst of the right testis. The males measure 0*25 mm., the 

 females 0-32 mm., and the larvae cvi mm. in length. The author 

 is of opinion that the animal perhaps a fertilised female was 

 introduced by a catheter, and, as a matter of fact, it was after- 

 wards found that the patient had had once the catheter passed 

 in India while suffering from pernicious fever. 1 



[Cheyletus mericourti, Lab. (Acaropsis mericourti, Moq. Tand.). 



This mite has been described from three specimens found in 

 pus which flowed from an abscess in the ear of a naval officer, 

 produced by inflammation of the auditory passage. Where the 

 mites came from we do not know, as they were found near the 

 Bank of Newfoundland. F. V. T.j 



8. Fam. Sarcoptidce (Itch Mites). 



Small mites without eyes and tracheae, and with delicate, transversely- 

 striated cuticle. The mouth-parts form a cone, over which the shield-shaped 

 upper lip protrudes ; the chelicerae are scissor-shaped ; the pedipalpi 

 (or maxillary palpi) have three joints ; the legs are short and compact, 

 and composed of five segments ; the terminal joints have pedunculated 

 suckers (ambulacra) or a long bristle. The larvae are six-legged. They 

 live on or under the skin of birds and mammals, on which they produce 

 the skin disease known as scabies, or itch. 



[The SarcoptidcB attack the epidermis of animals and man, living as 

 permanent parasites. The punctures they produce are followed by the 

 formation of more or less thick crusts or scabs, beneath which the mites 

 live and breed. Most are oviparous, some ovo viviparous. The eggs are 

 minute, ovoid, with a thin semi-transparent shell. They incubate in a few 

 days, varying from two to ten or eleven, as a rule. Generally sarcoptic 

 diseases lie dormant in winter and revive in spring and summer in man ; 

 but in animals with long wool, such as sheep, they are most active during 

 winter, although revival of active reproduction takes place in spring. 



Speaking generally for the Sarcoptidae, there are three distinct stages 

 in the development of the male, four in the female, as follows : 



(1) The larva. In this stage only three pairs of legs occur. 



(2) The nymph, in which a fourth pair of legs appear, and which thus 



1 Trouessart, E., " Faux parasit. d'une esp. de Sarcopt. detnticole dans un kyste 

 du testicule chez I'homme " (C. R. soc. biol., Paris, 1900, Hi., p. 742) ; " Deuxieme note 

 suv I' Hist, spermat. et sa pv'es. dans un kyste du testic. chez I'homwe ('ibid., p. 893). 



