234 J. L. LECONTE, M. D. 



Mandibles very long and slender, acutely toothed near the middle. Length 

 1.7 mm ,• .07 inch. 



%. — Eighth ventral segment with a small triangular impression. 



Two specimens, banks of the Colorado River, California, at Fort 

 Yuma. 



OXYTEI.rS Grav. 

 The species of this genus are less numerous than those of Bledius, 

 and do not seem to be capable of arrangement into well-defined groups, 

 which are separated by any important structural diflferences. They 

 are nevertheless easily recognized by size, color and sculpture, while 

 in most of them the male sexual characters are quite distinct, even in 

 the most nearly allied species. 



Prothorax coarsely sculptured, more or less shining 2. 



Prothorax very finely strigose, quite opake 11. 



Prothorax finely sparsely punctured, shining, without grooves; black, legs and 



elytra bright yellow 1. iucolumis. 



2. — Head prolonged behind the eyes 3, 



Head rounded immediately behind the eyes, which are prominent; front flat, 

 opake ; prothoracic grooves deep, elytra rugosely punctured ; piceous, base 



of antennpe and legs testaceous 2. sculptns. 



3. — Sides of prothorax crenulate; prothoracic grooves deep 4. 



Sides of prothorax entire 5. 



4. — Piceous, front flat, opake, base of antennae and legs testaceous. ..3. rugosus. 



Usually black, front convex, shining 4. niger, n. sp, 



5. — Front concave, apical margin elevated 6. 



Front flat, not margined at apex; head with long parallel impressions 8. 



6. — Prothoracic grooves deep, entire, front deeply concave 7. 



Outer grooves feeble; posterior impressions of head short. 



5. pensylvanicus. 



7. — Posterior impressions of head parallel 6. fiii^cipenuis. 



Posterior impressions of head converging 7. convergent, n. sp. 



8. — Vertex convex, feebly channeled 9. 



Vertex flat, not channeled; head very dissimilar in the sexes; prothorax 



strongly punctured, dorsal grooves deep 8. insiguitus. 



9. — Elytra strongly punctured, prothoracic grooves deep. ..9. puuctatus, n. sp. 



Elytra more depressed and more densely punctured 10. 



10. — Front polished, dorsal grooves distinct 10. nitidulns. 



Front opake, dorsal grooves distinct 11. sobriuu!^, n. sp. 



Front opake, dorsal grooves obsolete 12. placusinus, n. sp. 



11. — Anterior tibije slender, truncate at tip, dorsal segments smooth 12. 



Anterior tibiae as usual, obliquely emarginate on the outer side; dorsal 



segments densely punctulate 13. depressus. 



12. — Grooves of prothorax deep, head less opake 14. nanus. 



Grooves of prothorax feeble, head and prothorax entirely opake. 



15. exiguus. 



