No. 3-] POD ARK E OBSCURA VERRILL. 411 



the cross and rosette cells to the upper ends of the entomeres 

 (Text-Figs. 3 and 4). From the pointed upper ends of the 

 entomeres in Text-Fig. 5, I believe that the connections exist 

 also in later stages, though I have not been able to make 

 them out on preserved material. Professor E. A. Andrews, 

 who kindly examined some of my preparations at my request, 

 informs me that these processes are undoubtedly protoplasmic, 

 but that he is unable to determine from preserved material 

 whether they are protoplasmic streamings, such as have been 

 described in other animals (see No. 2), or remnants of the 

 primitive continuity which has never been lost. For our 

 present purpose the question is immaterial. Of importance is 

 the fact that protoplasmic connections do exist between blasto- 

 meres of relatively late cleavage stages. 



The embryo is now composed of sixty-four cells, divided as 



follows : 



1st Quartette 32 



2d " 16 



3d " 8 



4th " 4 



Entomeres 4 



Three of the quadrants are exactly alike and the fourth differs 

 from them merely in the possession of the small cell, X1.2, 

 which lies at what will be the posterior end of the body. 



Up to this stage it is evident that Podarke agrees in the 

 character of its segmentation with other annelids and with 

 gasteropods and lamellibranchs. In all cases three quartettes 

 of ectomeres arise in alternating directions. In all cases one 

 member of a fourth quartette is budded off, and this cell is 

 wholly or partially composed of the definitive mesoblast. Usu- 

 ally but not always {e.g., Nereis) the other three members of 

 this fourth quartette appear. Inasmuch as they, together with 

 the remaining macromeres, give rise to the entoderm, the dif- 

 ference is merely that in the one case this division takes place 

 at the surface, in the other, after invagination. 



On the other hand, Podarke differs from most other annelids 

 in two important features. The cells of the second and those 



