Xvi ILLUSTRATIONS. 



159. Nycteribia Hermanni, 386 



160. Feet of the fly, greatly magnified, four figures, 391 



161. Flea, magnified, 392 



162. Velvet spring-tail, magnified, 394 



163. American spider (Mygale avicularia) destroying 



a bird, 395 



164. Muscular ribbons for moving the wings in Syrphus 



inanis, magnified, two figures, 397 



165. Syrphus, 398 



