PLATE XXXIX. 



Sem^eostomites zitteli (p. 7(1). 



Natural size, from a photograph. (After Haeckel. ) 

 a. Grastral cavity. 

 t>,— 6 4 . The 4 oral arms. 

 c,-c e . The 3-sided pyramidal adradial papillte between the external corners of the gastral pouches 



and the genital pouches. 

 d,-d 4 . The 4 gastral pouches. 



/. The thickened mound-like ring which defines the peripheral boundary of the gastral pouches 



and the genital pouches, 

 e. The smooth zone. 

 </,-</.,. The 4 genital pouches. 

 h. The ring canal. 

 i. The marginal lobes. 



k. Radial canals (fc, perradial canals; fc„ interradial canals; fc, adradial canals). 

 1. Marginal tentacles. 

 7)i . Periphery of the zone of rays formed by the marginal tentacles. 



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