Zool.— Vol. I.] TORREY—MONOGENESIS IN METRIDIUM. 355 



complete mesenteries of the bud (seen in cross section in 

 fig. 10$). Pairs 1 and 3 are bent sharply from their courses 

 in entering the bud. One member of pair 3 does not reach 

 the oesophagus of the parent just below the oesophagus of 

 the bud, which accounts for the imperfect pair 3' in the 

 bud. A ring of stomata pierces the mesenteries around the 

 mouth of the bud (fig. \oc) . Neither the siphonoglyph of 

 the parent nor the corresponding pair of directives {D, fig. 

 10a) enter the bud, where no such structures were seen. 

 When formed they must arise independently of those of 

 the parent. The two cesophagi, however, are in communi- 

 cation, and probably have been from the first. 



In another instance, the siphonoglyph of the parent has 

 been drawn into the bud. Figure n« shows the parent 

 and bud, each sectioned through the oesophagus. The 

 parent has two siphonoglyphs, as indicated by the two pairs 

 of directives D and D' . Of these, pair D' alone enters the 

 bud, forming pairs d and d' . The distortion of the direct- 

 ives which results is accompanied b}^ a corresponding dis- 

 tortion of the siphonoglyph (fig. n#). Here the observer 

 is supposed to be looking through the mouth of the bud 

 from within the oesophagus of the parent; 5, 5 indicate the 

 siphonoglyph of the parent; e, e the edges of a cut across 

 the oesophagus of the parent and longitudinally to the 

 oesophagus of the bud, reaching the mouth of the latter; 

 r is a prominent ridge dividing the siphonoglyph into an 

 oral and an aboral portion and extending to the mouth of 

 the bud. The median groove of each portion reaches the 

 mouth margin distinct from the dividing ridge. This dispo- 

 sition of the siphonoglyphs, side by side, is unique in my 

 experience. 



Of the six polyps dissected, one of which presented two 

 oesophageal buds, the parental siphonoglyph in but three 

 (43 per cent.) entered the corresponding buds. It seems 

 highly probable, therefore, that the position of the bud 

 bears no necessary relation to the siphonoglyph nor the 

 greater mouth axis of the parent. For since the base of 

 any bud may include the mesenteries comprised in about 



