PHVLUIM CHORDA TA 



35 



scnsc-vc^iclc (srns. r-.s.) The jioslriKu- nairow part foiiiis tbr caudal 

 lioi-tii.u of the coiiti-al nervous system (^-.piiial nml). Masses of 

 luginent lu relation to the sense'vesiele eaily form the ludiment 



Fin. 734. — T^ater stages in tlic clevelopmeut uf Clavellina. A, a|ii.in.'xiuiately iiicdi;iii uptictl 

 section of a larva in which the medullary canal (ncuroe<plc) has become enclosed thnnigli.iut, 

 communicating with the exterior only by the neuropore at the anterior end and with the 

 archentcron by the ncurenteric canal ; }i, larva with a distinct rudiment of the tail and well- 

 formed mesuderm-layer and not(Jchord. Inciters as in preceding figure; in a'lditiun, uii..-i. 

 mesoderm, (After Van Benede)i and Julin.) 



of the two larval sense-organs, otocyst (or statocyst) and eye. The 

 part behind this presents a thickened wall with a narrow lumen. 

 This is known as the gavglion cf tlcc iriinh. The rudiment of the 



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