Notices of New Books. 8437 



a question that the nectar-drinkers of all countries are closely allied, 

 so closely indeed as to deceive the instructed eye of many an accom- 

 plished and observant traveller. 



Let us now examine the humming bird's mouth and compare it 

 with that of the nectar-drinkers on one side, and those of the goat- 

 sucker, the swift and the swallow on the other; and here let me observe 

 that if we once adopt a division, such for instance as that called fissi- 

 rostral, let it comprise all those birds which clearly possess the character 

 in question, but let us exclude all others which have been annexed 

 simply because they are difficult to dispose of in any other way, such 

 for instance as the kingfishers. The true fissirostral birds are the Capri- 

 mulgidae nocturnal, and the Hirundinidae diurnal ; and whether we 

 call them fissirostres or swifts we must regard them as a united and most 

 natural group, and must compare or contrast their most strongly pro- 

 nounced characters with those of the humming birds. First the gape 

 is an important element in the beak of every bird ; in the Nectarinia 

 and Trochilus the gape is extremely small ; it does not extend into 

 the cheek, it is scarcely perceptible when the mandibles are separated, 

 it is invisible when the mandibles are closed. Compare this with the 

 gape in Podargus, which is simply a nocturnal swift. I select the 

 Podargus because it exhibits the swift character in excess. When the 

 mandibles are separated for the purpose of gulping the enormous noc- 

 turnal insects which constitute their food the bird looks as though the 

 upper portion of the head must inevitably fall off, so widely does the 

 gape extend below and beyond the eye. Even when closed it often 

 curves upwards almost behind the eye : the reader unacquainted with 

 this extraordinary structure will do well to trace it through the genera 

 Batrachostomus, Podargus, Caprimulgus, Scotornis, Cypselus, Acan- 

 thylis and Hirundo. There is no halting-place between either two of 

 these genera. From the gape we pass easily to the external develop- 

 ment of the beak. I use the word external for want of a better; I 

 mean that portion projecting in advance of the face. In the seven 

 genera I have mentioned above the united mandibles, forming two sides 

 of an equilateral triangle, scarcely project beyond the face, and present 

 a strange contrast to the excessive gape. In Nectarinia and Trochilus 

 the beak is extended in a slender form and with parallel sides far in 

 advance of the face, and however the species (erroneously called genera) 

 either may vary in the curvature or length of their beaks, these cha- 

 racters of slenderness, parallelism and deficiency of gape obtain 

 throughout these groups, as regularly as the triangular form, absence 

 of extreme, development and excess of gape in the true fissirostres. 



