ARTHKOPODA 



181 



latter genera the cuticle is transversely striated and the legs are 

 provided with round, pedunculated suckers. The greater number 

 (400) of the species known to us belong to the Analgidse ; they are 

 found on and between the feathers of birds and, occasionally, within 

 the epidermis. Two varieties, Cytoleichus sarcoptoides, Megn., and 

 Laminosioptes gallinarum, Megn., which live in the cellular tissue 

 of the under-skin of fowls, belong to the genus Cytoleichidce. These 

 parasites may penetrate to other organs, where they usually become 

 surrounded by a cystic membrane and, eventually, calcify. They 

 differ from the Sarcoptidae 

 in the shape of the mouth- 

 parts (which, in Cytoleichidae, 

 are modified into a sucking 

 tube) and in the longitudinal 

 position of the vulva. Sarco- 

 ptidse live on and in the epi- 

 dermis of mammals and birds, 

 where they occasion various 

 forms of itch ; the mouth- 

 parts are separate and the 

 vulva are placed transversely. 

 Certain species burrow tun- 

 nel-like cavities under the 

 epidermis, one end of which 

 communicates with the sur- 

 face, while the blind end is 

 occupied by the female for 

 the purpose of depositing her 

 eggs. These tunnels may be 

 seen with the naked eye on 

 man ; they are up to 3 cm. in 



length and may be either FIG. 93. Sarcoptes scabiei. Male. Ventral 



Straight or crooked. 1 Owing as P ect - 200:1 - (After Fiirstenberg.) 



to the nature of the skin, 



they are less readily detected on animals. These burrowing mites 



belong to the genera Sarcoptes, Latr. and Notoedres, Eaill. They 



1 To obtain specimens for examination, the channel should be opened along its 

 entire length with a finely pointed needle, when the mite will be seen with the naked 

 eye as a shining whitish speck "at the end of the tunnel. Or a portion of the 

 epidermis may be cut out with a bent scissors, spread out upon a glass-slide, and 

 cleared with potassium solution or glycerine. The tunnels will be found to contain 

 blackish balls of faeces, eggs in various stages of development, empty egg-shells, and, 

 occasionally, the sloughed cuticle of the female Sarcoptes. The six-legged larvae will 

 not be seen, as, after emerging from the egg, they escape from the tunnel by means 

 of a special opening. 



