ORIBATIDJE. 663 



in large masses." " On the 3d of July the entire mass of eggs 

 seemed to hatch out at once, the shell opening like a clam and 

 releasing a six-legged insect." (Hays.) The opening of the 

 oviduct is just behind the head, between the anterior pair of 

 feet, so that the eggs appear as if ejected from the mouth. 



Another species is the Ixodes bovis (Plate 13, fig. 10), the 

 common cattle tick of the Western States and Central America, 

 which is allied to the European /. ricinus. It is very annoying^ 

 to horned cattle, gorging itself with their blood, though by no 

 means confined to them alone, as it lives indifferently upon the 

 rattlesnake, the iguana, small mammals, and undoubtedly any 

 sort of animal that brushes by its lurking-place in the forest. 

 It is a reddish, coriaceous, flattened, seed-like creature, with 

 the body oblong oval, and contracted just behind the middle. 

 When fully grown it measures from a quarter to half an inch 

 in length. We have received it from Missouri, at the hands 

 of Mr. Riley ; and Mr. J. A. McNiel has found it very abun- 

 dantly on horned cattle, on the western coast of Nicaragua. 



GAMASID^E Leach. These mites have scissor-like mandibles, 

 free maxillae, with joints of equal length, and hairy legs of 

 similar size and form, while the ocelli are obsolete. They live 

 parasitically on the bodies of other animals. The genus Gam- 

 asus has long mandibles, with curved, five-jointed, acutely 

 pointed maxillary palpi ; the body is oval, flattened, the skin 

 dense, and the first and last pair of legs are somewhat longer 

 than the middle ones. G, coleoptratorum Linn, is clear, red- 

 dish yellow, and about a third of a line long. It occurs in 

 Europe on beetles, especially species of Geotrupes and Necro- 

 phorus. The same, or a closely allied species, is found in this 

 country. Uropoda vcgetans DeGeer, a similar form, also lives 

 on beetles. The genus Dermanyssus has shorter jointed max- 

 illary palpi than in Gamasus. D. avium Duges lives on birds, 

 and D. pipistrell(K Gervais on bats. In Pteroptns the terminal 

 joint of the maxilla? is veiy long. Pt. vespertilionis Dufour is 

 a parasite of the bat. 



ORIBATID^E Nicolet. In these mites the body is very hard 

 and horny. The four-jointed maxillary palpi are short, with 



