Some of the bats captured northwest of Diriamba were taken in a net placed across the center of a water-filled, concrete cistern that was located in a large, open space used for drying coffee beans. Open at the top, the cistern was approximately 12 m in diameter, and the water level was approximately 3 m below the rim. Several _Artibeus jamaicensis_, _A. lituratus_, and _Molossus pretiosus_ were caught in the same net. Aside from bats removed from the net, a few _Eptesicus_ and _Molossus_ were retrieved from the water where they fell, apparently stunned, after colliding with the wall of the cistern. The fact that a number of decomposed bats of these two species were observed floating in the water indicated that such entrapment was not caused by the placement of our net.
A female pregnant with two embryos (crown-rump length 15 mm) was captured on 22 April, whereas one taken on 5 July was lactating. Adult males taken in March (two) and April (two) had testes 5, 7, 9, and 10 mm long, respectively.
_Specimens._--_Boaco_: Santa Rosa, 17 km N, 15 km E Boaco, 300 m, 2. _Carazo_: 3 km N, 4 km W Diriamba, 600 m, 2. _Chinandega_: 6 km N, 1 km E Cosigüina, 10 m, 3; Hda. Bellavista, 720 m, Volcán Casita, 1. _Matagalpa_: 1 km NE Esquipulas, 420 m, 1.
This small vespertilionid occurs throughout much of Central America, but the available material still is insufficient to permit an accurate assessment of geographic variation in that region. All but one of our specimens were trapped in mist nets. Those captured near Diriamba were taken in a net stretched across a trail bordered by high cut-banks, whereas those from other localities were netted over small streams. The one bat from Bellavista was shot as it foraged in the evening along trees bordering the hacienda yard.
Two females taken on 5 March each had swollen uteri and may have been in an early stage of pregnancy. Others taken on 13 July, 9 August, and 15 August were reproductively inactive. Males had testes that measured 2.5 (March), 3 (July), and 2 (August) mm.
We have compared our material with representative specimens from México of _R. parvula_ and _R. tumida_, as defined by Goodwin (1958); we are not wholly convinced that these are valid species (rather than variable geographic races of the same species). Certainly there is need for additional investigation of the problem. Our Nicaraguan specimens most closely resemble _R. t. tumida_ (see Goodwin, _op. cit._:3), to which they are tentatively referred.