24 PTERYLOGRAPHY. 



12. Interrupted like the preceding form, and furcate at the end of the anterior portion, but 

 the entire posterior part weak and very broad. Examples of this form, which is not frequent, are 

 furnished by Falco cachinnans and F. brachypterus (Plate II, fig. 5). The spinal tract of 

 Phcenicopterus (Plate IX, fig. 7) is very similar. It is also closely approached by the genera 

 Crax, Penelope, and Pterocles (Plate VII, fig. 4), although in these the posterior portion of the 

 spinal tract is so much widened that it coalesces with the lumbar tracts, as is likewise the case in 

 the Nasutas (with the exception of Diomedea, Plate X), and in the Unguirostrcs. This form then 

 approaches the fourteenth, in which, however, the broad posterior part has a central longitudinal 

 space, and is, therefore, cleft. 



13. Interrupted like the eleventh form, with a narrow and weaker posterior position; but 

 the division of the anterior part extends along the whole neck up to the occiput. I have only met 

 with this form once, namely, in Scopus umbretta (Plate IX, fig. 4). 



14. Interrupted between the shoulder-blades, the anterior part cleft at the end and tolerably 

 strong, the posterior part cleft throughout nearly its whole length, but more or less weakened at its 

 commencement; the outer margins are also gradually stunted, the inner ones sharply marked, 

 and the undivided extremity immediately before the tail is much narrower. This form passes 

 into the ninth, from which it cannot always be exactly distinguished ; it occurs frequently in 

 various families of birds. Among the diurnal rapacious birds the genera JRhynchodon (Plate II, 

 fig. 6) and Pandion possess it, and among the parrots Psittacus pullarius ; it also occurs in all 

 the genera of Longipennes (Plate IX), among the swimming birds ; in several genera of wading 

 birds, especially Limicolte, for example, in (Edicnemus, Charadrius (Plate IX, fig. 9), Strepsilas, 

 Totanus, Triuga, Numenius, Ibis, Limosa, Recurvirostra, Dromas, Scolopax, Cursorius, and 

 Glareola ; in some Fulicarice, such as Grus, Psophia (Plate VIII, fig. 4), Aramus and Podoa 

 (Plate VIII, fig. 9), and Storks (Pelargi), such as Tantalus and Platalea. 



15. Exceedingly like the preceding form, but with the cervical portion of the anterior region 

 of the tract so broad as to coalesce with the throat-tract to form a feather-coat covering the whole 

 neck, so that the lateral neck-spaces are wanting. I have met with this form only in Ciconia 

 (Plate IX, fig. 2) and Colymbus ILL. (Podiceps LATH., Plate X, fig. 11). The structure in 

 Ph<nicopterus (Plate IX, fig. 7) is similar; but I have already referred this genus to the twelfth 

 form, on account of the undivided dorsal portion. It is also worthy of notice that the division 

 of the cervical portion does not become visible only between the shoulders, but much farther 

 forward upon the hinder surface of the neck. Hence the two long arms of the tract run parallel 

 to each other, whilst the much shorter ones of the preceding form are very distinctly divergent. 



16. Continuous and very broad, but weakened, and especially stunted at the margin of the 

 covered part ; longitudinally divided by a narrow space on the neck and between the shoulders. 

 A spinal tract of this form occurs in Buceros (Plate VI, fig. 2), in the Unguiro&tres (Plate X), 

 and in Eudytes (Plate X, fig. 12), Aha (Plate X, fig. 14), and Una (alle]; it is similar in 

 Proccllaria glacialis (Plate X, fig. 2), P. capensis, Dysporus (Plate X, fig. 9), and Halieus. In 

 other genera of the Steganopodcs, especially in Phaeton, Plotus, and Pelccanus, the spinal tract is 

 much broader and coalesces with the humeral and inferior tracts, so that a nearly continuous 

 feathery covering is produced, 



17. Imperfect, the cervical portion being deficient; two fine spinal tracts running between 

 the shoulder-blades issue from the lateral neck-tracts, which are here present, but soon terminate, 

 even before reaching the extremities of the shoulder-blades. Corresponding with these are two 



