The MALES differ in having the antennæ as long or longer than the thorax; the _labrum_ transverse, linear, and the _abdomen_ usually elongate and cylindrical, and much longer than the head and thorax.
1. _xanthopus_, Kirby, ♂ ♀. 4-5 ½ lines. (Plate IV. fig. 1 ♂♀.) _Lasioglossum tricingulum_, Curtis. 2. _quadricinctus_, Fabricius, ♂ ♀. 4-4½ lines. _quadricinctus_, Kirby. 3. _rubicundus_, Christ. ♂ ♀. 4-5 lines. _rubicundus_, Kirby. 4. _cylindricus_, Fabricius, ♂ ♀. 3-5 lines. _malachura_, Kirby. _fulvo-cincta_, Kirby. _abdominalis_, Kirby. 5. _albipes_, Fabricius, ♂ ♀. 3-4 lines. _albipes_, Kirby. _obovata_, Kirby. 6. _lævigatus_, Kirby, ♂ ♀. 3-4½ lines. _lugubris_, Kirby. 7. _leucozonius_, Schrank, ♂. 3-4½ lines. _leucozonius_, Kirby. 8. _quadrinotatus_, Kirby, ♂ ♀. 2-3 lines. 9. _sexnotatus_, Kirby, ♂ ♀. 10. _lævis_, Kirby, ♀. 4 lines. 11. _fulvicornis_, Kirby, ♂. 4 lines. 12. _minutus_, Kirby, ♂ ♀. 2½-3½ lines. 13. _nitidiusculus_, Kirby, ♂ ♀. 2-3 lines. 14. _minutissimus_, Kirby, ♂ ♀. 1½-2½ lines. (Plate IV. fig. 3 ♂ ♀.) 15. _flavipes_, Kirby, ♂ ♀. 3-4 lines. (Plate IV. fig. 2 ♂ ♀.) _seladonia_, Kirby. 16. _Smeathmanellus_, Kirby, ♂ ♀. 2½-3½ lines. 17. _æratus_, Kirby, ♂ ♀. 2½-3 lines. 18. _leucopus_, Kirby, ♂ ♀. 3-3½ lines. 19. _morio_, Kirby, ♂ ♀. 2-2½ lines.
This genus was named by Latreille from _ἁλίξω_, to _crowd_, or _collect together_, from the fact of their nidificating in numbers on the same spot.