PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



Vol. 99 Washington : 1949 No. 3248 



ADDITIONS TO THE ECHIUROID FAUNA OF THE 

 NORTH PACIFIC OCEAN 



By "Walter Kenrick Fishek 



The material upon which this paper is based consists of a specimen 

 donated by Dr. J. E. Lynch, of the University of Washington, and 

 others dredged off the coast of California by the steamer Alhatross 

 in 1904. The Albatross specimens are a part of a considerable collec- 

 tion of unworked sipmiculoid and echiuroid worms, accumulated by 

 the late Prof. H. B. Ward, which did not become available for study 

 until after the publication of my "Echiuroid Worms of the North 

 Pacific Ocean-' (1946). About a third of this collection, including 

 some of the echiuroids of California, had deteriorated beyond re- 

 demption. What remains is of considerable interest. There is a 

 new and primitive genus of the Bonelliidae, while Arhynchite, sup- 

 posed to lack a proboscis, can now be shown to possess a well-devel- 

 oped one. 



I have used this opportunity to revise the keys to the genera of the 

 families Echiuridae and Bonelliidae. 



SYNOPSIS OF GENERA OF ECHIURIDAE 



a\ Two circles of caudal setae Echiurus Gu^rin-Meneville, 1831 



a -. No posterior setae present. 



ft '. No differentiated thicker bands in longitudinal muscle layer. 

 c\ Nephrostome of nephridia without elongated spirally coiled lips. 



d \ Neurointestinal blood vessel in direct connection with dorsal vessel by 

 a ring vessel at end of foregut ; segment of intestine between ring 

 vessel and beginning of siphon short and with ciliated groove; 

 nephrostome with inconspicuous lips; proboscis not especially ex- 

 panded at tip, often deciduous Thalassema Lamarck, 1801 



822650—49 1 479 



