354 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



which it rested was exceedingly flat and formed a decided 

 lobe connected by an isthmus of about half its diameter 

 with the parent. The walls of the lobe were quite thin, 

 enclosing a portion of the cavity of the parent. On April 

 14th the only change was a greater attenuation of the con- 

 necting isthmus. On April 23rd the bud was free. Neither 

 individual showed the least sign of rupture ; the base of the 

 bud was definitely contoured before separation took place. 

 This, therefore, is not equivalent to the laceration described 

 by Andres, where the fragment is either torn away, or is 

 detached by degeneration of the intermediate tissue. 



At least eighteen days, in all probability longer, were 

 consumed in completing the process. The bud possessed 

 one siphonoglyph and six and one-half pairs of complete 

 mesenteries. 



On May 2nd, a slight constriction was observed between 

 a second polyp and its marginal bud, producing a lobe simi- 

 lar to but less pronounced than that mentioned in the first 

 case. The foot disk was elongated in the plane passing 

 through the two individuals. On May 6th, the mesenteries 

 of the bud, as indicated on the foot disk, radiated around 

 the oral-aboral axis. Three only belonged also to the 

 parent. No further change has been noted. 



(b.) Budding in the (Esophageal Region. — Six cases of 

 this mode of monogenesis have been dissected. The earli- 

 est stages have not as yet been obtained. The advanced 

 stages appear at first sight identical with cases of unequal 

 fission ; but it may be seen in an external examination of a 

 typical specimen that the mesenteries of the bud are contin- 

 uous with those of the parent. This continuity demonstrates 

 that this is a case of budding and not fission: since the two 

 sets of mesenteries of two individuals formed by the latter 

 process are almost totally independent of each other (fig. 9). 



Upon dissection it was found that three pairs (1, 2, 3) of 

 complete mesenteries of the parent (seen in cross section 

 in fig. iort) and all the incomplete mesenteries included 

 between them, enter the bud B. The three pairs of com- 

 plete mesenteries form the six pairs (1, 2, 3, 1', 2', 3',) of 



