170 STRUCTURE OF HUMMING BIRd's TONGUE — LUCAS. 



In both Colaptes and Trochilns tbeceratobranchials are moderate, the 

 epibrancbials extremely long. 



Basibrancliial is wanting in Col- 

 aptes, very small and cartilaginous 

 in TrocMlus. 



The base of the Humming Bird's 

 tongue is formed of the soft, fatty, 

 fibrous envelope of the basihyal, 

 which, when the tongue is pro- 

 truded, stretches like a spiral 

 spring, and like a spiral spring 

 contracts as the tongue is with- 

 drawn. 



As the tongue is extended the 

 ceratobranchials are apposed and 

 pressed forward into this fibrous 

 sheath, and even when at rest these 

 little bones lie close together, only 

 separating when the tongue is con- 

 vulsively retracted, as in the act 

 of gasping. 



The soft base is succeeded by the 

 dense, cartilaginous sheath of the 

 ceratohyals, and this practically 

 consists of two portions, that invest- 

 ing the osseous part of the cerato- 

 hyals and that surrounding their 

 cartilaginous anterior portions. 



In badly preserved specimens 

 this latter part can be slipped ott* 

 intact, and its structure readily 

 studied. 



At first the cartilaginous sheath 

 forms a single tube, somewhat 

 elliptical in transverse section, 

 grooved along the center above 

 and below, and showing a slighter 

 groove on the ui)per exterior sur- 

 face. 



The central grooves indicate the 

 })resent division of the tube by a ver- 

 tical partition, the lateral grooves 

 the formation of a fiange along the 

 outer edge. 



A little more than halfway between base and tip the tongue becomes 

 forked, each division being a rod bordered by a wide flange of thin 



Fir,. I. riyoid of Selanphortis rii/iis X 8.c/i»/', car- 

 tilii<;inon.s iiroloiiK-it ion of the ctiratoliyal^t. A por- 

 tion of tlie surroiniilinjislieath is shown, the diflVr- 

 encc. in Mm sliailiiij; indie atingwliere the lenitoliyal 

 Hheatli becomes detaehed ; rliy, eoratoliyal ; bin/, lia- 

 sihyal; bbr, basihrancliia] ; chr. eeratobranchial. 



Only the distal portions of tlie epibrauchials are 

 shown. 



Fi(?. II. Hyoidof Oolaptes auratus X 2| Letters 

 aa before. 



