The Mariana subspecies of the Pacific sheath-tailed bat (Emballonura semicaudata rotensis) (payeyi, paischeey) is a small, insectivorous (insect-feeding), sac-winged bat in the family Emballonuridae, an old-world group with an extensive tropical distribution. It is a relatively small bat species with an approximate forearm length of about 1.8 in, 45 mm, long. It has a wingspan of eight to nine inches and has a pronounced thumb with a claw is located on the leading edge of each wing. Males weigh 0.2 ounces, 5.5 grams on average, and females weigh about 0.24 oz., 6.9 g. The pelage varies in color from brown to dark brown dorsally with a paler underbody. The common name sheath-tailed bat refers to the nature of the tail attachment, which involves a short, narrow tail emerging from a more anterior sheath-like membrane.