118 



DR. C. F. SONNTAG ON THE ANATOMY 



result of contractuie of the muscles. It is necessaiy, therefore, 

 to examine fresli material if one desires to study these characters 

 properly. Spenking generally, the real fissures are regular and 

 symmetrical, or iiearly so. They are complete or incomplete, the 

 former extending right across the dorsum, and the latter 

 stretching onh^ from the median fissure to the edges of the 

 tongue. They m.ay be straight or curved, with their convexities 

 forwards. 



In the Lemurs and Marmosets, they are shallow, broad, and 

 curved ; there are one or more complete ones behind the apex, 

 and several incomplete ones behind these on both halves of the 

 dorsum. In the Stoat, the fissures are narrow and deep, and 

 they pass in straight lines obliquely forwards and outwards from 

 the median fissure to the lateral borders of the organ. 



The arrangement of the papillae on these fissures and ridges 

 varies. In the Stoat they are only on the ridges, but in the 

 Lemurs and Marmosets they aie on either. 



Text-figure 8. 



LEMUfiS STOAT 



iJiffereiit forms of transverse fissures and ridges on the dorsum of the tongue. 



Tntermolar Elevation. 



In many animals the posterior part of the oral division of the 

 dorsum is elevated, therel)y pi-oducing the posterior lobule or 

 intermolar elevation, so-called from its situation. In the Ornitho- 

 rhynchusit appears as a broad and expanded part of the dorsum, 

 and it bears two triangular processes, or lingual teeth, on its 

 anterior border. These are of value to the animal when it 

 catches its food while swimming in the w^ater, for they direct the 

 insects into the cheek-pouches, whence they can be removed for 

 eating when the animal is at leisure. 



Tb.e Rodentia have well-developed elevations, wdiich offer a 

 marked contrast to the iow-lying anterior part of the dorsum. 

 Each of these divisions has a different function to perform. 

 The papillose anterior part is gustatory, whereas the posterior 

 lobule raises the food up to the molar teeth. 



The elevations differ in tlie abruptness in which they rise up 

 from the posterior end of the anterior division. 



The Lingual Papillce. 



The lingual papillte are of three kinds — circumvallate, fungiform, 

 and conical. At the sides tliere are a number of fissures and 



