12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



always larger than those of the female. Never has the reverse been 

 found in the 25 species that I have examined. This sex difference 

 applies to the heart in several species, and in Amasilia edward, 

 Amazilia tzacatl, Lampomis castaneoventris, and Selasphorus scintilla 

 it applies to the heart and pectoralis-supracoracoideus. Hearts range 

 from 1.65 to 3.25 percent of the body, pectoralis-supracoracoideus 

 from 21.7 to 33.1 percent. The supracoracoideus, ranging from 6.6 

 to 12.2 percent, is the largest of all birds studied. The "rest" is small, 

 ranging from 1.75 to 4.79 percent, and leg muscles are very small, 

 being only a little more than 1 percent. Wings range from 3.1 1 to 

 5.70 cm. 2 per gram; tail from 1.57 to 2.95 cm. 2 per gram; and buoy- 

 ancy index from 1.31 to 3.09. 



Trogonidae. — Trogons make short, rapid flights among the trees 

 to catch insects. Their flight muscles (29 to 32 percent) are slightly 

 larger than those of nightjars. Their hearts are also larger (1.05 to 

 1.29 percent), but the wings are smaller (buoyancy index, 3.68 to 

 3.91) and much wider (aspect ratio, 1.9 to 2.1) for flight among 

 foliage. Like the nightjars, their legs are small (2.4 to 3.1 percent). 

 The wings and glide areas of Pharomachrus, Trogon massena, and 

 Trogon melanurus are smaller than those of the other three species 

 of trogons measured. 



Alcedinidae. — The fairly large wings (buoyancy index, 3.09 to 

 3.68) enables the kingfisher to fly swiftly in short flights. The hearts 

 of these birds are large, especially in the smaller species (1.02 to 

 1.35 percent). The flight muscles (24.5 to 26 percent) are about the 

 size of those in the nightjars, and the legs are small (2.48 to 3 percent). 



Momotidae. — Motmots perch for long periods in one place (lower 

 extremities 6 percent). Their flight is undulating, their wings are 

 large (buoyancy index, 3.85) and broad (aspect ratio, 1.70), and they 

 have long, ornamental tails. The small hearts are indicative of limited 

 activity (0.39 to 0.49 percent). 



Bucconidae. — Although most species of puffbirds are sedentary, 

 they sally forth occasionally to capture insects (flight muscles, 24 to 

 28 percent ; buoyancy index, 3.4 to 3.56). Their lower extremities are 

 of moderate size (4 percent), and their hearts are small 0.45 to 

 0.58 percent). 



Capitonidae. — Barbets are weak fliers (flight muscles, 18.7 per- 

 cent) but have large lower extremities (9.4 percent) and larger hearts 

 (0.74 percent) than do the puffbirds, although they also remain in one 

 spot for a long time. 



Ramphastidae. — The restlessly active toucans are weak fliers 

 (flight muscles, 20 to 23 percent; hearts, 0.62 to 0.81 percent), but 



