44 THE VOYAGE OF H.M.S. CHALLENGER. 



are clearly developed in specimens of Bi^anchiostoma helcheii (?") of only half the size 

 of this specimen. 



Gonads not fully developed, extending from the first to the twenty-sixth myocomma, 

 and forming two series in the middle. The atrial cavity extends somewhat behind the 

 supposed position of the atrial pore. 



