24 
epithelial scales, hair, feathers, etc., of the host. The last two fami- 
lies are chiefly of interest to the yeterinarian as producing yarious 
forms of mange. Only two families are blood-sucking, the Ixodidsd 
(s. 1.) and the Gamasidx. The role of the former (ticks) in the trans- 
mission of disease has already been mentioned. A few species of the 
Trombididx are known to attack man; a laryal form (Leptus autum- 
nalis, L. americanus) is the well-known ^‘red bug” or “chigger,” also 
known as the ^‘haryest mite” in England and the ^^bete-rouge” in 
South American countries. In Japan the Tsutsugamushi disease or 
Kedani disease, frequently fatal, is due to the bite of the “akamushi” 
or “red mite.” This disease has recently attracted considerable 
attention; the etiology is unknown. 
Among the Gamasidse the “chicken mite” or “red spider louse” 
frequently bites those who yisit houses m which fowls are kept. The 
Gamasidse form a larger and more widely distributed family than the 
Ixodidse (s. 1.), but by reason of their small size and apparent harmless- 
ness they haye been but little considered. A number of species liye 
on decomposing yegetable and animal matter, others act as com- 
mensals upon beetles, reptiles, birds, and small mammals. Gamasi- 
dse, which are true bloodsuckers, are found upon lizards and snakes 
{Ophionyssus natricis Megnin); upon yipers and water adders they 
attack the cornea, rendering it opaque, the reptiles becoming blmd in 
consequence and dymg of staryation. Dermanyssus galUnse is a 
great pest to poultry and horses and eyen attacks man, withdrawing 
blood through the punctures made by its pointed mandibles. A 
number of species infest sparrows, canary birds, and parrots. A 
great number of small mammals are affected, including rats, held 
mice, moles, rabbits, etc. Upon bats a yery large species {Pteroptus 
vespertilionis) , popularly belieyed to be a bedbug, is found. The 
number of species of Gamasidse is legion, and doubtless when more 
attention is paid to this family many others will be discoyered. 
THE GAMASID^. 
The following brief description of the structure and habits of the 
Gamasidse is taken in part from Banks.® 
In general the Gamasidse are broad and flat, with a chitinous 
integument. Eyes are absent, but numerous sensory “hairs” on 
yarious parts of the body make up for this deficiency. Many forms 
are rapid in inoyement when disturbed. The mouth parts in many 
species can be withdrawn into the body. The head or capitellum 
can also be considerably retracted. The mandibles, two in number, 
are usually chelate, with toothed Angers. In some mites they are 
a Banks, X.: A treatise on the acarina or mites. Proc. TJ. S. Xat. Mus., vol. 28, 
pp. 1-114, 1904. 
