No. 1. — Preliminary Account of Planktonemertes Agassizii^ 

 a new Pelagic Nemertean. ^y W. McM. Woodwouth. 



Since the final report on the Nemerteans taken by the " Albatross " 

 expedition cannot be ready for publication in the near future, owing to 

 absences of the writer from Cambridge, the following brief preliminary 

 account of a new pelagic Nemertean in the Albatross collections is now 

 presented. No free swimming Nemertean has been described since the 

 appearance of Moseley's ^ accounts of the two specimens of Pelago- 

 nemertes taken by the " Challenger." The Challenger material was 

 afterward reported on in detail by Hubrecht,^ and more recently Btir- 

 ger,^ in his great monograph, has made two distinct species out of the 

 two specimens taken by the Challenger merely upon an examination of 

 Moseley's sketches, basing his distinction upon the differences in the 

 number of lateral diverticula of the intestine in the two specimens. 



The form to be considered here, like Pelagonemertes, was taken in 

 the Pacific Ocean, and in trawls from considerable depths. While the 

 Challenger specimens came from latitudes well outside of the tropics, 

 and from the western part of the Pacific, the specimens taken by the 

 Albatross came from near the equator in the eastern part of the ocean. 

 There are many points of resemblance between the two forms, resem- 

 blances in form, color, and even finer structure, which will not be dis- 

 cussed here, but a careful comparison with the detailed description by 

 llubrecht shows differences in structure of such fundamental importance 

 that it has been necessary to establish a new genus in Moseley's family 

 Pelagonemertidie. 



1 Moseley, H. N. On Pelagonemertes Kollestoni, Ann. Mag. Nat. ITist., Vol. 



XV. p. 165, 1875. A Young Specimen of Pelagonemertes RoUestoni. Ibid., Vol. 



XVI. p. 377, 1875. 



2 Hubrecht, A. W. W. Report on the Nemertea collected by H. M. S. Chal- 

 lenger. Challenger Report. Zoology, Vol. XX., 1887. 



3 Biirger, O. Nemertinen. Fauna u. Flora Golfes von Neapel, Monographie 

 XX., 1895. 



VOL. XXXV. — NO. 1. \ 



