AUTHORITIES.--Mortillet, _Le Signe de la croix avant le Christianisme_ (Paris, 1866); Bingham, _Antiquities of the Christian Church_; Lipsius, _De Cruce Christi_; Lady Eastlake, _History of our Lord_, vol. ii.; Cutts, _Manual of Sepulchral Slabs and Crosses_; (Anon.) _Handbook to Christian and Ecclesiastical Rome_, part ii. (London, 1897); Veldeuer, _History of the Holy Cross_ (reprint, 1863). (T. M. F.)
[1] Derivatives of the Latin _crux_ appear in many forms in European languages, cf. Ger. _Kreuz_, Fr. _croix_, It. _croce_, &c.; the English form seems Norse in origin (O.N. _Krosse_, mod. _Kors_). The O.E. name was _rod_, rood (q.v.).
[2] The acceptance of this word as the English equivalent for this peculiar form of the cross rests only, according to the _New English Dictionary_, on a MS. of about 1500 in the Lansdowne collection, which gives details for the erection of a memorial stained-glass window, "... the fylfot in the nedermost pane under ther I knele ..."; in the sketch given with the instructions a cross occupies the space indicated. It is a question, therefore, whether "fylfot" is a name for any device suitable to "fill the foot" of any design, or the name peculiar to this particular form of cross. The word is not, as was formerly accepted, a corruption of the O. Eng. _feowerfete_, four-footed.
CROSSBILL (Fr. _Bec-croisé_, Ger. _Kreuzschnabel_), the name given to a genus of birds, belonging to the family _Fringillidae_, or finches, from the unique peculiarity they possess among the whole class of having the horny sheaths of the bill crossing one another obliquely,[1] whence the appellation _Loxia_ ([Greek: loxos], _obliquus_), conferred by Gesner on the group and continued by Linnaeus. At first sight this singular structure appears so like a deformity that writers have not been wanting to account it such,[2] ignorant of its being a piece of mechanism most beautifully adapted to the habits of the bird, enabling it to extract with the greatest ease, from fir-cones or fleshy fruits, the seeds which form its usual and almost invariable food. Its mode of using this unique instrument seems to have been first described by Townson (_Tracts on Nat. Hist._, p. 116, London, 1799), but only partially, and it was Yarrell who, in 1829 (_Zool. Journ._, iv. pp. 457-465, pl. xiv. figs. 1-7), explained fully the means whereby the jaws and the muscles which direct their movements become so effective in riving asunder cones or apples, while at the proper moment the scoop-like tongue is instantaneously thrust out and withdrawn, conveying the hitherto protected seed to the bird's mouth. The articulation of the mandible to the quadrate-bone is such as to allow of a very considerable amount of lateral play, and, by a particular arrangement of the muscles which move the former, it comes to pass that so soon as the bird opens its mouth the point of the mandible is brought immediately opposite to that of the maxilla (which itself is movable vertically), instead of crossing or overlapping it--the usual position when the mouth is closed. The two points thus meeting, the bill is inserted between the scales or into the pome, but on opening the mouth still more widely, the lateral motion of the mandible is once more brought to bear with great force to wrench aside the portion of the fruit attacked, and then the action of the tongue completes the operation, which is so rapidly performed as to defy scrutiny, except on very close inspection. Fortunately the birds soon become tame in confinement, and a little patience will enable an attentive observer to satisfy himself as to the process, the result of which at first seems almost as unaccountable as that of a clever conjuring trick.