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 4); the name adopted by me occurs 
previously in R. Wagner's Lehrb. der vergl. Anat. p. 5 76. 
5. Cilice (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 (hamatse; 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 
* Nitzsch calls it the Hyporrhachis (under-shaft), which name, how¬ 
ever, can only be applied to the shaft of the accessory plumule. It might 
rather be named Hypoptilium. The name plumula accessoria presupposes 
that its parts must be called rhachis, pogonium, &c., accessoria. 
