-> ) 



C. M. CHILD. 



of slow contraction and extension occurs, the same planula being 

 at times almost worm-like in form or contracting to a form con- 

 siderably shorter and broader than Fig. 5. The original apical 

 end still precedes in locomotion, as indicated by the arrows (Figs. 

 2-5). After a day or more of continued swimming, either free 

 or along the bottom, the planula attaches itself by the original 



3 



apical end, which shortens and thickens (Fig. 6), and the basal 

 end begins to elongate to form the stem (Fig. 7) and this in turn 

 gives rise at its tip to the first hydranth (Fig. 8). Stolons may 

 arise later as outgrowths from the attached end. Stem and 

 stolon are easily distinguished since the stem grows erect or free 

 from the substratum and has an annulated perisarc, while the 

 stolon grows in contact with the substratum and is without annula- 

 tion. This course of development is essentially similar to that 

 described by other investigators for various other hydroid species. 



