61 



at the posterior- end of the planula, lie :;ays: "In :i living 

 olanula it is easy to :nake out the posterior end, an ecto- 

 dernial invap^ination , which looks vory T.uch like the :Toiith 

 of an invagiiiation gastrula, but this resemblance is mislead- 

 ing, for the careful study of a sirdlar structure in the 

 planula of Eutin a shows that the invagination has no con- 

 nection vath the digestive cavity, but is an ectoderteal 



gland for the attachment of the planula." From my observatioa 



e 



I am forced to regard this struture, which he describes, 



as a variatior; rather thar a normal feature. It seems to be 

 an abnormal occurence v/hich is found only rarely. Among 

 the many specimens wh''ch I studied both in life and from 

 preserved material, such an invagination was met ■.ith only 

 on one occasion. Then it v/as at the anterior end of .the 

 Planula instead of the posterior. These f e j-tur as nre clear- 

 ly abnormal features of the developing Tur ritorsis 

 Planula. 



