NEW AMERICAN ACARINA. TRANS ACTTIONS OF THE AMERICAN ENTOMOLOGICAL SOCIETY. voIvUnie: XXII. ON THE ORIBATOIDEA OF THE UNITED STATES. BY NATHAN BANKS. The Oribatid mites are easily recognized by the division of the body into two regions, cephalothorax and abdomen, by the jDresence of a seta to a small pore near each posterior corner of the cepha-lothorax, by having the legs in the normal position (not separated in pairs), and by their coriaceous tegument. Because of this latter character they have often been called " beetle-mites." The body of an Oritabid is readily divided into two parts, the smaller and anterior portion is the cephalothorax, the posterior part is the abdomen ; beneath the tip of the cephalothorax is a distinct, articulated por-tion, the true head. To the head is attached the mandibles and palpi, both of minute proportions. The cephalothorax is usually more or less triangular ; a plate of tegument frequently extends from the base of the abdomen down upon the cephalothorax, thus making the surface of the cephalothorax continuous with that of the abdo-men, and the dorsal outline entire. This plate is known as the tectal plate or tectum. Whenever there is a distinct break in the dorsal outline of the body at the junction of the cephalothorax and abdo-men the tectal plate is considered to be absent. And on this char-acter the true Oribatidfie is divided into two sub-families, the Nothrinse in which it is absent, and Oribatinie in which it is present. Most of the genera of the former have but one claw to tarsus, and most of the genera of the latter have three claws ; but there are prominent exceptions in each group. In some forms the tectal plate is free at TRANS. AM. ENT. SOC. XXII. (1) JANUARY, 1895.