Plate i. 



Fig. I. Mertensia ovum, immature. Agassiz Laboratory, Newport, 



Rhode Island, September 7, 1895. 

 Fig. 2. Pleurobrachia brunnea sp. nov., mature. In the ocean 5 miles 



off Bamegat Bay, New Jersey, October 16, 1904. 

 Fig. 3. Pleurobrach-ia brunnea. Side view of apical sense-organ. 

 Fig. 4. Pleurobrachia brunnea. View of one of the side branches of 



the tentacles. 



Drawn from life, by the author. 



