INTRODUCTION. Vii 
trees, which lie scattered over the damp ground of the forest, we frequently observe the 
slow-moving Oribatide, or the soft velvety Trombidide, the larve of which may be 
found attached to the wings of dragon-flies, grasshoppers, and other insects. The 
larger species of Muscide carry on their thorax the hypopial forms of Tyroglyphide, 
just as they do in Kurope; and the Belostomide, which we find in the ponds of the 
high valleys and barrancas of Guatemala, have their legs infested by the larve of 
Hydrachnide, in the same way as are those of Kanatra and Nepa in Europe. It isa 
remarkable circumstance that not one of the species described in the following 
memoir represents a generic type entirely new or peculiar to Central America. With 
the exception of the holotropical genus Megisthanus (fam. Gamaside), and the chiefly 
American genus Amblyomma (fam. Ixodide), all the genera enumerated by me likewise 
occur in the Palearctic Region. 
reographical Distribution of the Genera of Acarids hitherto found in Central America. 
Fam. TROMBIDID. 
Gen. TromBipiuM. 
Palearctic Region (Europe, N.E. Siberia). 
Nearctic R. (U.S.A.). 
Neotropical R. (Central and South America). 
‘Ethiopian R. (Senegambia, Gold Coast, S.W. Africa, Cape of Good Hope). 
Gen. RuYNCHOLOPHUS. 
Palzearctic Region (Europe). 
Nearctic R. (U.S.A.). 
Neotropical R. (Central and South America). 
Gen. Linopopes. 
Palearctic Region (Europe). 
Neotropical R. (Guatemala, Buenos Ayres). 
Fam. ACTINEDIDZ. 
Gen. ACTINEDA. 
Palearctic Region (Europe, Siberia). 
Neotropical R. (Central and South America). 
Fam. TETRANYCHID. 
Gen. TETRANYCHUS. 
Palearctic Region (Europe). 
Nearctic R. (U.S.A.). 
Neotropical R. (Mexico, Guatemala). 
