466 PICID.I. 



It is now generally conceded that the structure of all 

 animals is, as remarked by Macgillivray, in every way corre- 

 lated with their mode of life, and in no one animal more so 

 than in any other ; but sometimes we are able to trace 

 clearly the connexion between a curious structure and its 

 results, and this is especially so as regards the tongue of 

 the Woodpeckers. That of the present species, with its 

 appendages, has been frequently figured and described, and 

 reference may be particularly made to the description and 

 figures given by the careful author just named (Br. B. iii. 

 pp. 57-60, pi. xv.). This organ is capable of extraordinary 

 protrusion, a property obtained by the elongation of the 

 posterior branches of its bones (the ceratohyal and apohyal), 

 which, after diverging and extending backwards and down- 

 wards in a long loop, pass upwards round the back of the 

 head and forwards over the right orbit till they are attached 

 to the cavity of the right nostril.* Each of these elonga- 

 tions is accompanied by a slender muscle, one end of which 

 is attached to the tip of the apohyal and the other to the 

 lower jaw, so that by its contraction the loop is straightened 

 and the tongue thrust out : another pair of muscles folded 

 twice round the upper part of the trachea, and adhering 

 thereto, are attached to the anterior part of the tongue (the 

 basihyal), and by their contraction the tongue is withdrawn. 

 The tip of the tongue is a horny point beset with a few stiff 

 barbs, pointing backwards. On each side of the head, 

 behind and below the ear, is a large elongated parotid 

 gland, whence a duct passes forward to the symphysis of 

 the mandible, and just where the tip of the tongue habitually 

 rests. Through this duct the glutinous secretion of the 

 glands flows copiously, keeping the tip constantly moist, and 

 thus fitted for securing the smaller insects on which the bird 



* Nitzsch found that they are sometimes, but rarely, diverted to the left side 

 (Naumann, Vceg. Deutschl. v. p. 252). In other Picidce, as Macgillivray 

 observes (Audubon, Orn. Biogr. v. p. 542 and B. Am. iv. p. 289), the arrange- 

 ment is different. For instance in Dryobates villosus, the prolonged bones recurve 

 round the right orbit to reach the line of the posterior angle of the eye, while 

 in Sphyrapicus varius, as well as in the two species next to be described, they 

 extend only to the middle of the occiput. 



