116 AMERICAN HYMENOPTERA. 



he used, the presence or absence of lateral face marks seems to be 

 constant, and is used as one of the first divisions in the table to the 

 females. The coloration of the tubercles, however, is not so relia- 

 ble, although as a general rule it is a good character. I have a 

 specimen of duiila with dark tubercles, also one of pacifica, yet these 

 species are placed under the division having them light or cream 

 colored. In the case of the males the shape of the apical plate is 

 very constant, though often difficult to describe in words, but this is 

 provided for by the sketches. 



It is my pleasure to express thanks to Mr. Myron H. Swenk for 

 his valuable criticisms and for looking over the manuscript, to Prof. 

 L. Bruner, Mr. Henry L. Viereck, Prof. T. D. A. Cockerell, Mr. 

 C. F. Baker and Abbe V. A. Huard for invaluable assistance ren- 

 dered, and to many others who have by furnishing specimens or by 

 other means aided me. 



CERATIIVA Latreille. 

 Synon : Zadontomerus Ashmead, Trans. A. Ent. Soc, xxvi, p. 69. ^ 



Mr. Viereck has examined the mouth parts of a specimen of the 

 type series of C. tejonensis Cresson, the type of the genus Zadonto- 

 merus, and finds the the maxillary palpi six-jointed, as in the other 

 species. The triangular tooth on the hind femora is present in a 

 majority of the species of Ceratina, and the shape of the apical plate 

 is hardly generic in character. 



SYNOPSIS OF MALES. 



1. Black bees, with white marking and whitish pubescence; very small species; 



3-3.5 mm 2. 



Metallic-blue or green bees ; both large and small species 3. 



2. Apical plate concave, the concavity shallow; clypeus entirely white; the en- 



tire face beluw the antennae white (Southwestern United States). 



arizonensi^ Cockerell. 

 Apical plate crescent shaped, the corners acute ; clypeus and two good-sized 



lateral face marks white (Texas) luiiala u. sp. 



Apical plate rounded, and with an acute triangular tooth medially; clypeus 

 and two small lateral face marks white (Belize, British Honduras). 



atrata n. sp. 



3. Apical plate with two very small teeth medially ; small species 4. 



Apical plate rounded, truncate, pointed, or obtusely bilobed 5. 



4. Face very narrow; mandibles with only a small white spot; teeth of apical 



plate blunt and indistinct; 3 mm bakeri n. sp. 



Face broader; anterior margin of mandibles with a heavy white border; teeth 

 of apical plate pointed and well defined ; 3.5 mm- ■ .diodoiltst n. sp. 



