d. Four pairs of short legs; species inhabiting moss or water. Water-bears. Tardigrada
dd. Two pairs of clasping organs near the mouth, instead of legs, in the adult; worm-like creatures parasitic within the nasal passages, lungs, etc. of mammals and reptiles ([fig. 148]). Tongue worms. Linguatulina
ACARINA[E]
a. Abdomen annulate, elongate; very minute forms, often with but four legs ([fig. 62]). Demodicoidea
b. With but four legs of five segments each. Living on plants, often forming galls. Eriophyidæ
bb. With eight legs, of three segments each. Living in the skin of mammals. Demodicidæ
To this family belongs the genus Demodex found in the sebaceous glands and hair follicles of various mammals, including man. D. phylloides Csokor has been found in Canada on swine, causing white tubercles on the skin. D. bovis Stiles has been reported from the United States on cattle, upon the skin of which they form swellings. D. folliculorum Simon is the species found on man. See [page 78].