CACOSOMA. 39 



27. Halictus providens. 



Female. Length 3 lines. — Black, with the abdomen towards the 

 apex very pubescent. Head obovato, the face very finely punc- 

 tured, the vertex sparingly so and shining, the face with a thin 

 hoary pubescence. The mesothorax smooth and shining, sparingly 

 punctured, and with a longitudinal central impressed line in front 

 extending to the disk ; the postscutellum with pale downy to- 

 mentum; the metathorax truncate, the truncation smooth and 

 shining, the base of the metathorax with radiating strioe; the 

 wings hyaline and iridescent, the nervures and teguhe pale testa- 

 ceous ; the logs with whitish pubescence, the apical joints of the 

 tarsi testaceous. Abdomen impunctate, the base very smooth and 

 shining; the sides of tho second, and the third, fourth, and follow- 

 ing segments covered entirely with thin pale pubescence, that at 

 the sides of the anal rima pale fulvous ; beneath, the segments are 

 fringed with long pale pubescence. 



Hah. Guatemala. 



28. Halictus placidus. 



Female. Length 4^ lines. — Head and thorax blue, abdomen ferru- 

 ginous. Head subopaque, the clypeus slightly produced, truncate, 

 and with a few large punctures ; the flagellum fulvous beneath ; 

 the face thinly covered with pale fulvous pubescence. Thorax 

 slightly shining; the metathorax truncate, its base smooth and 

 shining ; wings hyaline and iridescent, the nervures pale testaceous ; 

 legs black, the apical joints of the tarsi ferruginous ; the tarsi with 

 bright fulvous pubescence within. Abdomen shining, its extreme 

 base black. 



Hal. Chili. 



CACOSOMA, Smith. 



Head about the same width as the thorax; eyes subreniform, 

 the ocelli in a triangle on the vertex ; the scape of the antenna? two 

 thirds of the length of the flagellum, which is subclavate ; tongue 

 very short, not longer than the paraglossoe ; the labial palpi 4-jointed, 

 the first joint subclavate and as long as the two following united, 

 the second and third joints short, stout, and clavate, the apical joint- 

 much narrower and filiform ; the maxillary palpi 6-jointed, the 

 three basal joints short, stout, and clavate, the fourth and fifth joints 

 slender and slightly thickened at the apex, the apical joint about 

 the same length as the fifth joint, and slightly attenuated towards 

 the apex, which is blunt. The anterior ivings with one marginal and 

 three submarginal cells : the first submarginal cell a little longer 

 than the second and third united, the second narrow and very 

 slightly narrowed towards the marginal ; the third twice the width 



