708 



ZOOLOGY 



SECT. 



od.ont 



FIG. 624. Triton rubicundus. Interior of 

 the buccal mass, from above, magnified. I. jaw, 

 left jaw ; odont. lateral surface of odontophore ; 

 rad. radula ; r. jaw, right jaw. 



presents a central axis, connected at right angles with which are two 

 rows of close-set delicate lamellae. Like the ctenidium, it is closely 

 applied to the wall of the mantle-cavity throughout its length. 

 The laminaa of the osphradium are supplied with nerves which 



ramify over them, and its 

 function seems to be to ascer- 

 tain the condition of the 

 water that enters the mantle- 

 cavity. 



Digestive System. The 

 mouth, situated at the an- 

 terior end of the introvert, 

 leads into a large chamber 

 with muscular walls, the 

 buccal cavity (buc.). At the 

 sides of the entrance to this 

 cavity the investing cuticle is 

 thickened to form two dis- 

 tinct horny plates the jaws 

 (Figs. 623, 624, and 625, 

 jaw}. The jaws are flexible, 

 and on examination under the microscope are found to be com- 

 posed of numerous rows of minute bodies, the denticles ; the 

 anterior edge is minutely denticulated. From the floor of the 

 cavity rises an elevation, the odontophore (Fig. 623, od., Fig. 624, 

 odont.), which is somewhat elongated in the direction of the long 

 axis of the body and compressed laterally. Over the summit of 

 the odontophore 



runs longitudin- *o***n> 



ally a narrow 

 strap - like body, 

 the radula or 

 lingual ribbon 

 (Figs. 624 and 

 625, rod.}, beset 

 with numerous 

 minute horny 

 teeth arranged in 

 transverse rows. 

 Posteriorly this 

 toothed ribbon 

 passes into a nar- 

 row curved pouch 

 -the radular sac (Fig. 623, rad. s, Fig. 625, rad. sac.) extending 

 backwards from the posterior and lower aspect of the buccal 

 cavity. Anteriorly it does not extend beyond the odontophore- 

 prominence. The latter contains cartilages (Fig. 625, cart.) 



CU-f't- 



FiG. 625. Triton rubicundus. 



vertical section of Imucal cavity. 



l>iaj:ramniatie lunui' udina i 

 bod. mv. body-r;i\ it y : curl. 



cartilage of odontophore ; Jan-, ridit jaw ; as. oesophagus : 

 radula ; rail. sac. radula sac. 



