356 



HANDBOOK OF INVERTEBRATE ZOOLOGY. 



9. This mandible is shown in section at e, in the ventral 

 margin of the mouth. 



10. A rounded body, the tongue {i}, projects into the 

 cavity of tlie moutli on its ventral side. 



b. In a section near the middle of the buccal body (Fig. 

 187), notice: — 



1. The commissures {b, b), which run down into the head 

 from each of the brachial ganglia. At first these com- 

 missures lie in the axes of the arms, but in a section a 

 little farther from the anterior end they will be found to 

 be in the space around the buccal body. 



Fui. 1S7. 



Fig. 187. — Section a little f urtlier back, less highly magnified. 

 (Drawn from nature by W. K. Brooks.) 

 k. Eadula. Other letters as in Fig. 186. 



2. The buccal body is, at this level, almost entirely made 

 up of the large mandibular muscles (Fig. 187, g). 



3. In the central axis, but nearer to the dorsal than to 

 the ventral surface, notice the pharynx (c). 



4. Around the dorsal edge and sides of the pharynx the 

 cut section of the dorsal mandible (d). 



5. Projecting into the cavity of the pharynx on the ven- 

 tral or siphonal side, is a muscular, tongue-like body, the 

 odoniophore^ or the muscle of the lingual ribbon (k). 



i 



