104 BULLETIN OF THE 



To my mind, the most significant difference between the two groups 

 exists in the fact that the outpocketing to form the stomach arises from 

 the oral end of the future ahinentary tract in Endoprocta, and fi'om the 

 anal end in Ectoprocta. One is led to believe that in the ancestral form 

 either two nearly equally important outpocketings from both the oral 

 and anal sides existed, or that the two existing methods are remnants 

 of a method different from either (such as the formation of the whole 

 alimentary tract at once), or, finally, that the Endoproct condition repre- 

 sents the ancestral one, and that the rectal evagination has secondarily 

 become of greater importance in Ectoprocta, and that tlie oi-al evagina- 

 tion has become less significant. Oka ('90, pp. 134, 141) has recently 

 asserted that in the poly[)ide buds of the statoblast and adidt colony of 

 a Pectinatella of Japan (P. gelatinosa) the asophagus and stomach are 

 formed by one evagination, which acquires secondary connection with 

 the rectum. This condition reminds one, then, of Endoprocta. I must, 

 however, doubt the accuracy of Oka's conclusions until more satisfactory 

 evidence is forthcoming ; the moi-e so, since Pectinatella magnifica, 

 Leidy, presents a method of budding exactly comparable to that in 

 Cristatella and Plumatella, as my own sections show with sufficient 

 clearness. 



The homology of the Ectoprocta and Endoprocta implies a homology 

 of their larvre, and demands that the life history of the two groups should 

 be directly comparable. 



It is well known from the researches of Hatschek ('77) on Pedicellina, 

 and of Harmer ('85) on Loxosoma, that the surface of the larva which 

 bears the mouth and anus, i. e. its oral side, corresponds with that of the 

 blastopore. How, then, is the oral aspect of the Ectoproct larvse, which 

 I have tried to show is opposite to the pole of the blastopore, to be 

 homologized with this ? 



The mouth and anus of the Endoproct larva undergo a rotation after 

 the larva has settled, so that they come to occupy the pole opposite to 

 that at which the blastopore was. This stage of the Endoproct larva 

 is comparable to the whole larval stage of Ectoprocta. I believe the 

 two stages to be homologous, and tliat, just as polypides are pre- 

 cocioudy formed upon the Phylactolfcmatous larva, its larval digestive 

 tract having dropped out from the ontogeny, so the mouth and anus of 

 GvmnnlaBmata are precociousUf formed on the pole opposite the blasto- 

 pore, the primitive stage during which they existed at the blastoporic 

 pole having dropped out of the ontogeny. 



It is well known from the works of Harmer ('8G) and Seeliger ('89), 



