BIRDS OF BRITISH GUIANA. 



associated by previous authors with ThamnopUlus leachi Such, as 

 the type; but, when one compares that bird with the figure, it will 

 be easily seen that Eeichenbach could not have intended it, as the 

 bill is not anything like it. The species was originally, and has for 

 many years been, placed in the genus ThamnopUlus Vieillot, where 

 it was equally out of place, as it is so entirely different from that 

 genus, which was founded on Lanius doliatus Linn. I have pro- 

 posed, therefore, the new generic title Mackenzicena, with the 

 following characters: — Head not crested, no concealed white 

 dorsal patch, tail much longer than wing. Bill short and stout, 

 the depth about two-thirds the length of the exposed culmen ; the 

 wing, which is shorter than the tail, has the fifth primary longest ; 

 the tail is rounded and much graduated, the two middle feathers 

 longest. Coloration : the male is black with ovate white spots and 

 bars to the feathers, and the female is brown marked with buff. This 

 genus is named in honour of Mrs. Helen Mackenzie McConnell. ] 



PREDERICKENA Chubb. 



FredericJcena Chubb, Ann. & Mag. Nat. Hist. (9) ii. 1918, July 1, 

 p. 123. 



Fig. 6. — Frederic^ena viridis. 



The chief characters of this genus are the nuchal crest, which is 

 composed of rather broad feathers with rounded tips ; no con- 

 cealed white dorsal patch ; the bill is short and stout, the depth 

 being about half the length of the exposed culmen ; the wings are 

 rounded, the fourth, fifth, and sixth primaries longest and sub- 

 equal, the seventh is between the third and fourth ; the tail, which 

 is also rounded and graduated, is about two- thirds the length of 

 the wing. Coloration : the male is almost uniform, but the female 

 has the tail and entire under surface barred. 



