AQUATIC EARTHWORMS 



639 



10 (n) Setae of dorsal bundles all uncinate. . Paranais Czerniavsky 1880. 

 P. litoralis (Miiller) reported as abundant on the New England coast and may occur in adja- 

 cent fresh waters. The first dorsal setae are on V. 



11 (10) Dorsal setae nearly straight, slightly toothed or simple-pointed. 



Ophidonais Gervais 1838. 



O. serpentina (Miiller) may be easily recognized by the 

 small irregularly distributed dorsal setae; by the four large 

 transverse pigmented areas on the anterior region, and 

 by the relatively large size. Length 25-30 mm. 



FIG. 983. Anterior end of Ophidonais serpentina. X 40. (After 

 Piguet.) 



1 2 (9) Capilliform setae present in dorsal bundles 13 



13 (21) First anterior dorsal setae on V or VI 14 



14 (18) Posterior end not modified into a gill-bearing respiratory organ; 



first anterior dorsal setae on VI 15 



15 (16, 17) One or more capilliform setae of VI much longer than those of 



other somites and equal to three or four times the diameter 

 of the body Slavina Vejdovsky 1883. 



S. appendiculata (d'Udekem), common in some parts of the United States, has body surface 

 studded with sensory papillae and with foreign booiies. 



16 (15, 17) Prostomium elongated to form a proboscis; dorsal setae of VI similar 



in length to those of other somites. Stylaria Lamarck 1816. 



5. lacustris (Linnaeus) has proboscis flanked by promi- 

 nent lateral prostomial lobes (Figs. 980 and 984) . 5. fos- 

 sularis Leidy lacks the lateral prostomial lobes (Fig. 984). 

 The former is abundant and widely distributed in the 

 United States while the latter is reported only very infre- 

 quently. 



FIG. 984. Prostomium and proboscis, Stylaria. A, S. lacustris; 

 B.S.fossularis. X4. (Original.) 



17 (15, 16) Without proboscis; dorsal setae of VI similar in length to those of 



other somites Nais Miiller 1774. 



Several species without conspicuous differences are reported from the United States. N. 

 is Muller is one of the best-known species and N. communis Piguet is very common. 



elinguis 



18 (14) 



19 (20) 



Posterior end modified into a gill-bearing respiratory organ, the 

 branchial area 19 



Ventral margin of the branchial area with a pair of long processes. 



Aulophorus Schmarda 1861. 

 A . furcatus (Oken) has the first dorsal setae on V and 

 has two pairs of well-developed gills. 



A. vagus Leidy crawls or floats about in a tube made 

 from bryozoan statoblasts and bits of vegetation. It has 

 the first dorsal setae on VI and has only slightly devel- 

 oped gills. 



FIG. 985. Posterior end of Aulophorus furcatus. X 40. (After 

 Bouseneld.) 



