516 THE ANIMAL PARASITES OF MAN 



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

 0*32 mm., and the larvae 0*1 mm. in length. The author is of opinion 

 that the animal perhaps a fertilized female was introduced by a 

 catheter, and, as a matter of fact, it was afterwards found that the 

 patient had once had the catheter passed in India while suffering from 

 pernicious fever. 



It would here rather appear to be the case of a facultative para- 

 sitism of an otherwise free-living species. Histiogaster cntonwphagits, 

 Laboulbene, is found occasionally in collections of insects feeding 

 on larger species containing much fat ; the species also occurs on dry 

 cantharides; it appears to belong to the region of South Europe, 

 where, however, it is widely spread. 



[Entomophagus occurs all over Europe and in America. It has 

 been described under the following names : Acarns mains, Shimer, 1868 

 (Trans. Illinois Hort. Soc.) ; Dermaleichns mali, Riley, 1873 (Rep. Ins. 

 Missouri, v, p. 87) ; Tyroglyphiis mali, Murray, 1877 (" Eco. Ent. Apt.," 

 p. 275) ; T. corticalis, Michael, 1885 (Trans. Roy. Micros. Soc., ser. 2, v, 

 3, p. 27, figs, i to 14) ; Histiogaster corticalis, Canestrini, 1888 

 (Prosp. Acarof., iii, p. 397) ; H. alenrophagns, Sicherin, 1894, Canestrini, 

 Prosp. Acarof., vi, p. 815. Trouessart's species is evidently distinct. 

 F. V. T.] 



Genus. Cheyletus. 



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 New- 

 foundland. This genus of Acari has enormous mandibles and a 

 peculiar tracheal system ; two ungues and appendages to the tarsi. 

 F. V. T.] 



Family. Sarcoptidae (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 chelate ; 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 SarcoptidcE attack the hairs, feathers or epidermis of birds, 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 (so called scab, mange and itch). Most are oviparous, some ovoviviparous. 

 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 



