368 Mr. T. D. A. Cockerell — Descriptions and 



smaller size the skull cannot be distinguished from that of 

 M. a. neglectus ; it differs quite strikingly from the skull of 

 mial in its smaller size, relatively greater zygomatic breadth, 

 broader brain-case, and longer basioccipital (17*3 °j of 

 condylo-basal length). For the cranial dimensions see table 

 on p. 367. 



Remarks. This mouse is apparently a dwarfed insular 

 development of M. a. neglectus, the form inhabiting the 

 Scottish mainland. The presence of such an animal on 

 Muck is the more interesting when we recall that on Eigg, 

 as on Skye, Mull, Jura, Islay, Gigha, and Arran the grass- 

 mice are either identical witli exsul or more nearly related to 

 it than to neglectus. It seems probable that Eigg and Muck 

 have been separated from each other for a very long time 

 and that Muck has been joined with the mainland at a more 

 recent date than that of the severance of most of the other 

 islands. 



XLTIT. — Descriptions and Records of Bees. — LIV. 

 By T. D. A. Cockerell, University of Colorado. 



Megachile vincta, Vachal. 



Two females from Guayaquil, Ecuador (Buchwald : Alfken 

 coll. 1). Previously known only from Arica, Chili. In one 

 the abdomen shows distinct green tints. The ventral scopa 

 is clear white, with a little black hair at extreme apex. 



Megachile pyrrhogastra, sp. n. 



$ . — Length about ] 2\ mm. 



Robust ; head and thorax black, with long pale ochreous 

 hair ; abdomen bright ferruginous, the first segment above 

 with ochreous hair, second to fifth with rather broad, entire, 

 orange-fulvous hair-bands; ventral scopa white, scanty and 

 fulvous on last segment ; extreme sides of third and following 

 segments with black hair, long and conspicuous, invading 

 the scopa, on the fourth. Wings strongly reddish, with an 

 orange tint. Legs black, the femora more or less stained 

 with red. Mandibles broad, quadridentate ; clypeus shining, 

 strongly punctured, the lower margin with two tubercles 

 close together ; antennae chestnut-red, dusky above ; meso- 

 thorax granular from very dense minute punctures; tegxilse 



