398 C. J. Sundevall on the Wings of Birds. 



Scapus (feather-spool ; " stjelk/' Markl.) is the name given 

 by Illiger and Nitzsch to the calamus and rhachis together. 



3. Radii or R. primarii (vane-rays), which issue from the 

 rhachis on both sides, close up to and from the horny lamella 

 of the upper surface. Together they form the vane (pogo- 

 nium). They are in general fine, filiform, and nearly cylin- 

 drical ; but in the large quill-feathers they are flattened, in 

 the form of narrow lamellae, which, however, are somewhat 

 prismatic, nearly like a knife-blade, so that the thinner, 

 smooth-edged margin is turned towards the reverse side of 

 the feather. The outer margin, which is somewhat thicker, 

 is furnished on both sides, both above and below, with secon- 

 dary vanes (see No. 4). Nitzsch calls the vane-rays Rami 

 (branches), which name is far less suitable than the denomi- 

 nation radii, long previously adopted by Illiger. 



4. Radii secundarii (secondary vane-rays, vane of the 

 second order) issue on both sides from the outer margins of 

 the Radii primarii : they issue from the outer side of the 

 vane-rays, just as the latter issue from the outer side of the 

 shaft. These are called Radii by Nitzsch ; Illiger called them 

 Radioli (Terminol. 1269 h) ; the name adopted by me occurs 

 previously in R. Wagner's Lelirb. der vergl. Anat. p. 576. 



5. Cili(e (Nitzsch) issue in the same way from the Radii se- 

 cundarii, and are extremely fine, hair-like, simple, and short. 

 In the middle of one side of the radii secundarii in most 

 feathers they are bent or hooked (hamatae ; they are then 

 called hami by Nitzsch), in order that they may firmly seize 

 the radii secundarii of the next radius. This is the cause 

 of the force with which, in most feathers, the vane hangs 

 together. In those feathers which have not coherent vanes, 

 the cilise are not hooked. 



6. Plumula accessoria (accessory plume, c) "^ is a small 

 shaft with its vane, constructed like the larger shaft and vane, 

 which in most small feathers issues from the margin of the 



* Nitzscli calls it the Hyporrhachis (under-sliaft), which name, how- 

 ever, can only be applied to the shaft of the accessory plumule. It might 

 rather bo named Ili/popfiliuni. The name 2}lii»tii'la accessoria presupposes 

 that its parts must be called r/iacJiis, po//oiu'um, Sec, accessoria. 



