PLOTOHELMIS. 143 



neuropodium with the distal end free; they are typically of a broadly sublanceo- 

 late form, with the apex often prolonged. (Plate 23, fig. 4). 



Localities. Paumotu Islands : Sta. 3691 (lat. 18° 55' S., long. 146° 32' W.) . 

 Surface temp. 78° F. 4 November, 1899. One specimen taken at 100 fms. to 

 surface. 



Off Peru: Sta. 4671 (lat. 12° 07' S., long. 78° 28' W.). Surface temp. 66° F. 

 20 November, 1904. Three specimens.. 



Between Callao, Peru and Easter Islands: Sta. 4679 (lat. 17° 26', long. 86° 

 46' W.). 300 fms. to surface. Surface temp. 69° F. 7 December, 1904. The 

 anterior end of a single very small specimen. 



This species in having the axis of the eyes strictly transverse agrees with 

 alhomaculatus Levinsen and gazellae Apstein. It differs from the former in the 

 form of the cirri and especially in having the somites ventrally entire instead of 

 conspicuously bipartite. From gazellae it differs in the position and form of 

 the median tentacle, this being attached much in front of the axis of the eyes 

 instead of somewhat caudad of this level; in the much larger, more folia- 

 ceous, and more ventrally placed paired tentacles; strikingly in the form and 

 position of the tentacular cirri; and decidedly in the form of the styles of the 

 notocirri. 



Plotohelmis, gen. nov.^ 



Rhynchonerella Greeff {nee Costa), Nova acta Acad. Caesareae Leop.-Carol., 1876, 39, p. 74; Apstein 

 {nee Costa), Ergebn. Atlant. Ocean * * * Plankton-exped., 1900, 2, H. b., p. 15. 



Body depressed, slender, tapered caudad, relatively long. Eyes very large. 

 Tentacles fine. Prostomium projecting conspicuously forward beyond the eyes. 

 Five pairs of tentacular cirri, of which two pairs are reduced in size. Parapodia 

 uniramous. Both ventral and dorsal cirri large and foliaceous. Neuropodia 

 without terminal appendages. Setae of two types, simple coarse ones and finer, 

 capillary, composite ones. 



Genotype. — P. alata, sp. nov. 



Rhynchonerella was established by Costa with his species gracilis manifestly 

 the type. Subsequently R. capitata Greeff, R. longissima Levinsen, and R. 

 fulgens Greeff were referred to the genus, Greeff's two species later proving to be 

 identical. Costa's species is now known to be identical with Greeff's nasuta, 

 the type of his genus Callizona, which must accordingly fall as a synonym of 



' 7rXcor6s, floating, ?X/iis worm. 



