8 PEOCEEDINGS OP THE NATIONAL MUSEUM vol.67 



. In this group falls also the simple fleshy tongues of the gallina- 

 ceous birds (fig. 7). 



2. Fish eaters, where the tongue is used to hold slippery prey. 

 In these it is found to be plentifully supplied with sharp, stiff 

 retrorse spines. These may be distributed over the whole sur- 

 face, as in the penguins, edging the lateral margin only as in the 

 fulmars and shearwaters (fig. 8), as a patch of stiff spines situated 

 at the base, as in the loons, or a double row on the surface, as in 

 mergansers (fig. 10). A distinction must be drawn between fish 

 eaters that use the tongue and those in which the food is bolted 

 whole, where it has lost its function and a different condition pre- 

 vails. 



3. A diet of a multiplicity of small things strained from the water 

 is associated with the complex tongues of the Anatidae (fig. 9). 



Typically it is roughly rectangular in shape and is thick and fleshy. 

 The tip is composed of a cornified rounded flaplike process. Pos- 

 terior to this the tongue is broad with a median groove and provided 

 laterally with a double row of heavy hairs, the upper overhanging 

 the lower like a thatched roof. Toward the posterior half the upper 

 row, by a process of agmination of the hairs, becomes converted to a 

 series of large, heavy spines, which vary in number with the differ- 

 ent species. Coincidentally the edges of the median groove become 

 cornified with rough, toothlike processes. Lateral to these the sur- 

 face of the tongue is nodular or papillar and plentifully supplied 

 with openings of ducts of muscous glands. The posterior portion of 

 the tongue is made up of a fleshy eminence heavily armed with 

 strong spines. 



The method of use is interesting. The tongue is depressed, allow- 

 ing water to run along the groove, it is then raised against the palate, 

 the water squirted out from the sides through the hairy edges, 

 straining out and leaving the solids. 



Considerable variation is seen, depending on the use of this organ 

 and the width of the bill. Thus in the geese and swans where it is 

 used for tearing up weeds and grasses it has become a very power- 

 ful tearing structure. In Cygnus buccinator, for example, the 

 edges of the median groove instead of consisting of rather rounded 

 eminences become very sharp, long tearing spines. 



A similar purpose is accomplished by Branta nigricans by con- 

 version of the entire lateral row of hairs into spines ; in other words, 

 all of the lateral hairs have become agglutinated into spines, and this 

 process extends quite to the tip. 



On the other hand the red-breasted merganser (fig. 10), having 

 taken to fish fare, has developed sharp dorsal spines and lost one 

 row of marginal hairs, tending to approach in type the fish eaters. 



