Plate 6. 



Obelia striata, page 9. 



Fig. 1. A part of a colony ; a, young gonothecpe ; b, a hydrotheca much less than the 

 usual size ; c, a hydrotheca of the normal size and shape ; d and e, hydrothecae 

 from the same stem showing a transverse constriction, x 80. 



Fig. 2. A part of another stem with normal hydrothecae and a perfect gonotheca. x 80. 



Fig. 3. Another hydrotheca from the same stem, x 80. 



Fig. 4. Two gonothecae on the hydrorhiza. x 80. 



Figs. 5, 5b, 5c. Three hydrothecae from one stem, x 80. 



Figs. 6, 0b. Two hydrothecae from still another stem, x 80. 



Fig. 7. A gonotheca containing the peculiar gonozooid. x 116. 



Fig. 8. A colony, natural size, attached to a shell. 



