110 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



Ualosydna lagunae Hamilton (1915, p. 235) is a Lci)idoiiotus. 

 Ualosydna leioscta Chamberlin (1919b, p. 2) is Arctonoe pulchra (Johnson). 

 Halosydna macroccphala Essenberg (1917, p. 53) is H. johnsoni (Darboux). 

 Halosydna succiniseta Hamilton (1915, p. 234) is Arctonoe vittata (Grube). 



HALOSYDNA LATIOR Chamberlin 



Halosydna latior Chambeelin, 1919b, p. 1 (California). 



Halosydna obtusa-cirrata Tbeadweix (1937b, p. 143) (Ix)wer California). 



Halosydna obtusa-crrrata Treadwell, from Lower California, com- 

 pares favorably with II. latior Chamberlin, from southern California. 

 H. latior is readily distinguished from other species of Halosydna by 

 its broad depressed form and its closely imbricated, broadly reniform 

 scales, which have a conspicuous fringe on the outer lateral border. 

 Another characteristic feature mentioned by Chamberlin, but not de- 

 scribed for //, ohtusa-cirrata., is the elongate nature of the nephridial 

 papillae ; they are about three times as long as thick. I have observed 

 tliis feature in numerous specimens deposited in the collections of the 

 University of California. 



Specimens of //. latior have been taken in abundance from the 

 deeper waters of southern California by expeditions of the steamer 

 Albatross. Many of these collections have not been reported upon. 

 They are deposited in the University of California and the United 

 States National Museum. 



HALOSYDNA LEUCOHYBA (Schmarda) 



Polynoii Icucohyba Sciimakda, 1861, p. 309 (Jamaica). 

 Halosydna leucohyha Websteb, 1884, p. 3u9 (Bermuda). 



Halosydna brevisctosa Trelvdwexl, 1902, p. IGG (U.S.N.M. nos. 16009-16012) 

 (Puerto Rico) ; not Kinberg, 1855, p. 385. 



Specimens of H. hrevisetosa Treadwell, from Puerto Rico, are all 

 representatives of //. Icucohyba (Schmarda) as redescribed by Web- 

 ster. H. brevisetosa Kinberg is thus not known outside of the eastern 

 Pacific. 



HALOSYDNELLA, new genus 



Resembling Halosydna Kinberg in prostomiiun and body contour 

 but longer. Differs from Halosydna in having about 45 setigerous 

 segments and 20 to 24 pairs of scales, inserted on segments 2, 4, 5, 7, 

 9 ... 23, 25, 28, 29, 32, and on every second or third segment more pos- 

 teriorly. Ventral setae distally entire or with a subterminal tooth 

 (fig. 36, c). Dorsal setae finer than ventral setae and ornamented with 

 transverse rows of spines. Notopodial setae may be absent from some 

 jjosterior parapodia. 



Type of genus: Halosydna australis Kinberg, from the La Plata 

 River. 



