Bangs — Rare or N'ot Well Knoivn Costa Rican Birds. 35 



Three forms are supposed to occupy Central America as follows: 



Microcerculus philomela Salv. Guatemala. Larger; less rufescent 

 brown . 



M. daul i as llidg. Eastern Costa Rica. Smaller; more rufescent l)rown. 



if. luscinia ^-dh'. Panama to southwestern Costa Rica. Smaller; with 

 underparts darker and much more uniform. 



The slight differences in size claimed for the various races do not appear 

 to hold — one male from El General, which should belong to M. luscinia, 

 supposedly the smallest race, has the wing 61.5, larger than in M. daulias, 

 considered to be the largest race. 



As to color, immature examples, that is those with dusky vermicula- 

 tions above, and with the underparts varied with V-shaped i)aler markings 

 and witli slight dusky bars on flanks, vary very much from one locality. 

 Two skins from Cerro Sta. Maria have whitish throats in marked contrast 

 to the color of the rest of the underparts ; another from the same place 

 has the throat dark grayish ))rown, not very ditterent from the color of 

 the breast and belly. One of the skins with a white throat has all the 

 feathers of the chest, breast and ])e]ly broadly edged with grayish-white 

 and whitisli V-shaped marking lower down on the same feathers. The 

 other white-throated one lacks the white edges to these feathers, but has 

 the pale V-shaped markings. The third, with a grayish-brown throat, 

 has no whitish markings below, but has the featlu'rs of the ])reast and 

 belly with dark grayish V-shaped markings. 



Two from Tenorio and one from I,a Mjagua are very similar to the 

 third just described from Cerro Sta. Maria. The female from La Vijagua, 

 which is in nearly fully adult plumage, is, however, vt-ry different, and 

 is hardly distinguis]ia])le in any way from the specimens from Chiriqui, 

 and I should unliesitatingly call it M. luscinia. It diflers only in having 

 some slight traces of dusky vermientations above and indistinct dusky 

 bands on the flanks — both probably last remnants of immaturity. 



Lastly tlie three fully adult specimens from the VolcAn de Chiriqui, 

 taken in March and April, and the four adults from El General, south- 

 western Costa Rica, in June and July, are all alike, except that the El 

 General skins are slightly paler, grayer brown on breasts and bellies, and 

 slightly more rufescent on flanks, diff'erences doubtless due to season, 

 especially as neither series runs perfectly constant in this respect, and one 

 skin from Chiriqui (the palest) practically matches one (the darkest) from 

 El General. 



It thus appears to me that tliree facts, at least, are obvious enough : 



(1.) Difl'erences of size in Central America specimens of Microcerculus 

 are not great enough or constant enough to be of diagnostic value. 



(2.) Specimens in immature plumage from one locality show a wide 

 range of variation in color and markings (possibly due to age of the indi- 

 vidual, it requiring more than one month to attain the adult plumage). 



(o.) Specimens in adult plumage, or nearly so, are subject to a slight 

 seasonal variation in color, but apart from this can not satisfactorily lie 

 distinguished from such remote places lying in such difl'erent general 

 faunal areas as northeastern Costa Rica on the one hand and south- 

 western Costa Rica and Chiricjui on the other. 



