DESCRIPTIONS OF GENERA AND SPECIES 287 



segment VI longer than the rest ; dorsal bundles of this segment contain three setae each ; 



in the following segments only one dorsal seta on each side. No glandular ventricle. 



Eyes present. Hob. — Neighbourhood of Philadelphia. 

 This species evidently belongs, by virtue of the specially elongated setae of the 

 sixth segment, to Vejdoysky-'s genus Slavina, which, as it appears to me, Vaillant 

 was right in joining with 'Nais' {=:Opsonais). N. gracilis, however, is probably not 

 identical with N. appendiculata, for Leidy makes no mention of the sensory papillae 

 which, if present, would hardly have escaped his attention. Furthermore, it seems to 

 differ in the limitation of the number of the dorsal setae, and in the absence of 

 a glandular ventricle. 



(6) Nais appendiculata, d'Udekem. 



N. appendiculata, d'Udekem, Bull. Acad. Roy. Belg. t. xxii, pt. ii. 1855, 



P- 552- 

 ^ Slavina appendiculata, Vejdovsky, SB. Bohm. Ges. 1883, p. 219. 

 ?N. escherosa, Geuithuisbn, Nova Act. Ac. Nat. cur. 1828, p. 409. 



Definition. Dorsal setae cainlliform only, those of sixth segment very much longer than those 

 of other segments. A row of sensory papillae upon all the segments of the body. Hah. — 

 Europe. 



There can be no doubt that Slavina appendiculata of Vejdovsky is the same species 

 as iV. appendiculata of d'Udekem. The characteristic sensory papillae are referred to 

 by d'Udekem as 'appendices couverts de spicules,' and figured (fig. 3 of his Plate 

 illustrating Memoir). It has been also thought to be identical with the N. lurida of 

 TiMM, with which, however, it cannot be confounded. 



The worm is figured, in addition to the above quoted authorities by Vejdovsky (24, 

 PI. iii, fig. 17-26), BousFiELD 1 (PI. xxxiii, figs, a, 3, 4, copies from Vejdovsky and 

 d'Udekem). 



(7) Nais lurida, Timm. 



N. Ixirida, Timm, Arb. Zool. Zoot. Wiirzb. 1883, p. 153. 

 Slavina lurida, Bousfield, J. Linn. Soc. 1886, p. 268. 

 Definition. Number of segments, 40; first pair of dorsal setae very long ; not more than two in 

 each bundle. Two rows of infegumental sense bodies on each segment. Hah. — Europe. 

 Bousfield has re-examined this species, and shown it to be quite distinct from 



