This paper brings together and summarizes available data on the genus Ghilianella in the Americas. Descriptions of the genus and subgenera are given, as well as a checklist of the 88 known species. The keys differentiate the 80 species of which specimens were available for study; they are expansions of those published in 1925 by McAtee and Malloch (the fine work of these authors has aided me greatly in the completion of this paper). Among the species treated in the following pages, 15 are described as new, 1 is redescribed, and the ''hypotypes" of 7 others are described. For 32 previously described species, notes are given on specimens examined, and the paper closes with notes on the 8 species not included in the keys. In the illustrations (see pp. 407-421) I have tried to keep together similar structures from the various species so that a comparison of them could be made.In this paper, the term "hypotype" is used to refer to a specimen herein described and belonging to the opposite sex of the corresponding holotype described by another author. Additional specimens of the hypotype are called "parahypotypes." Thus, I have followed the terminology suggested by Frizzell (1933).•College of Agriculture and Mechanic Arts, Mayaguez, Puerto Rico. 393

The new neotropical harpactorine genus Orbella is described and three new species are assigned to it. It is allied to Atrachelus Amyot and Serville and Corcia Stål. The males of Orbella lack claspers. A key is provided to separate these three genera.

Rasahus costaricensis n. sp. from Costa Rica is described and illustrated. New locality records are given for six other species of Rasahus.

Apronius planus, new species, is described from Peru and compared with the A. octonotatus species group. Important anatomical details are illustrated.

Se presenta una lista anotada de 29 especies de ácaros informados por primera vez en Puerto Rico. Para cada especie se incluye la localidad, el hospedero o hábitat, fecha de captura, el nombre del colector y el acarólogo que la identificó.

Paralienates hyalinus, from Dominican amber, is described.

Homalocoris punctatus n. sp. is described from Brazil, illustrated, and compared with allied taxa. A key to the six species in the genus is given.

The authors give morphological notes, observations on the biology, and provide keys to the species in Cricetopareis. C. brasiliensis, a new species, is described and illustrated.