FIG. 78. Obelia. A, portion of a colony with certain parts shown in longitudinal 

 section ( x 10) ; B, medusa ( x 5) ; C, the same with reversed umbrella ; D, the 

 same, oral aspect. Bd. i, 2, buds ; bis. blastostyle ; coe. coenosarc ; ect. ectoderm ; 

 end. endoderm ; ent. enteric cavity ; g. th. gonotheca ; h. th. hydrotheca ; /. litho- 

 cyst ; m. bd. medusa-bud ; mnb. hypostome or manubrium ; msgl. mesoglcea ; 

 mth. mouth ; p. perisarc ; P. /, 2, 3, polypes ; rod. c. radial canal ; t. tentacle j 

 vl. velum (From Parker and HaswelTs Zoology, reduced.) 



310 



! 



