TEETAN—TEETH 953 



TEETAN, TEETING, Orkney and Shetland names for the 

 Titlark. 



TEETH are so generally possessed by Vertehrata as naturally to 

 induce the supposition that the older Birds must have had them, 

 and many anatomists had been looking out for their traces. 

 Already in 1821 fitienne Geoffroy St.-Hilaire announced the dis- 

 covery, on the edges of the mandible and prsemaxilla in embryos of 

 Palxornis torquatus, of papillae, rich in blood-vessels and nerves and 

 containing globular bodies, which he likened to dental germs. His 

 son, Isidore, and Cuvier thought that these " germs " became sup- 

 pressed by the later development of the horny sheath of the bill. 

 In 1860 Blanchard {Comptes Eendus, 1. pp. 540-542) made micro- 

 scopical investigations on Cacatua and Melopsittacus, and described 

 plates of dentine, sent out from the edge of the underlying bone 

 and partly surrounding the papillse, which last were directly con- 

 nected with the periosteum. Subsequently Prof. W. Marshall 

 {cf. Thier-reich, Vogel, i. p. 499) examined a nestling of Nymphicus and 

 found clusters of calcareous deposit in the papillae of the still carti- 

 laginous mandible. He observed similar papillae in an embryo of 

 Aptenodytes, and his attention was drawn to a longitudinal groove ex- 

 tending along the edges of both the upper and lower jaw in the adult. 

 Dr. M. Braun {Arh. Zool. Inst Wurzhurg, 1879, pp. 161-204, pis. viii. 

 ix.) described and figured similar papillae in MelopsiUams, explaining 

 the so-called plates of dentine as calcified horn, and comparing the 

 papillae themselves with the horny serrations on the bill of the 

 Anseres. In 1880 Dr. Paul Fraisse {SB. Phys. Med. Ferh. Wilrz- 

 burg, XV. pp. iii.-ix.) re-examined these papillae, and concluded that 

 they were but cutaneous outgrowths, projecting into the super 

 imposed horny layers; which, being situated between the Malpighian 

 layer and the periosteum, became connected with the latter, the 

 capsule of supposed dentine consisting of peculiarly-modified and 

 occasionally calcified cells of the horny layer. Thus they bear a 

 striking but oidy a superficial resemblance to the germs of Teeth. 

 After all, then, Dr. Einsch's practical suggestion (Die Papageien, 

 p. 138) is right, and these papillae only ensure the firmer connexion 

 and better noui-ishment of the thick horny beak. They can be 

 easily seen by macerating a Parrot's beak and tearing oflF the cover- 

 ing, and are comparable with the long cutaneous i3apillce which 

 extend into the hoof of a horse. They occur numerously only in 

 Pdttaci and to a lesser degree in Anseres, but not in Eatitse, Gallinse, 

 Columbse, Accipitres or Corvidse, though present in the form of a 

 single long and soft projection at the tip of the praemaxilla and 

 mandible of many Birds with strong and hooked beaks. 



The total absence of dental germs in all recent Birds is of 

 course no proof that their ancestors did not possess such organs, 



