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PHYLUM TROCHELMINTHES 



329 



On the head are four tufts of flagella, which are partly sensory, partly 

 vibratile. The mouth, situated at the anterior end, leads by a narrow tube 

 into the thick-walled oesophagus. At the beginning of the latter are a number 

 of small chitinous denticles, and in front of them a circlet of setae. The 

 oesophagus leads to a wide elongated stomach followed by a short intestine 

 which terminates in an anal aperture at the posterior extremity. The 



FIG. 277. Chaetonotus maximus. 

 Highly magnified. (After Zelinka.) 



yld. 



FIG. 278. Chaetonotus maximus (or- 

 ganisation), brn. brain ; gld. adhesive 

 gland ; mes. mesenteron ; mo. month ; 

 oes. resophagus ; ov. ovum ; ovar. ovary ; 

 retr. retractor muscles ; vent. mus. ventral 

 muscle. (After Zelinka.) 



nephridia are a pair of unbranched coiled tubes each opening on the ventral 

 surface and terminating internally in a flame-cell. The nervous system con- 

 sists of a large dorsally and anteriorly situated cerebral ganglion or brain 

 giving off a pair of ventro-lateral longitudinal nerves. The sexes are united, 

 and there is no metamorphosis. 



