DESCRIPTIONS OF GENERA AND SPECIES 283 



I am inclined to think that FLOERICKE'S genus Caecaria will have to be incorporated with 

 Nais. He regards it as intermediate between Stylaria and Pristina. It has no eyes, a long prostomium, 

 and the dorsal setae begin on the sixth segment. In Caecaria rara the second, third, and fourth 

 dorsal bundles are much shorter than the others. In C. silesiaca only the first bundle is shorter. In 

 C. brevirostris all are equal. Pending further information, I leave the species as inceiiae sedis. 



N. claricornis of SARS (Beskrivelser og iagttagelser, &c., Bergen, 1835), ' s apparently a Tomopteris. 



N. bipunctata (DELLE CHIAJE), N. picta (DUJAEDIN), N. quadricuspidata (FABRICIUS) are also 

 Polychaeta. 



N. Carolina (BLANCHARD) is quite unrecognizable. 



N. scotica is referred to below. 



(i) Nais barbata, 0. F. MULLER. 



? N. barbata, O. F. MULLEB, Verm, terrestr., 1774, vol. i, pt. ii, p. 23. 

 Opsonais obtusa, GERVAIS, Bull. Ac. Roy. Belg., 1838, p. 17. 

 N. elinguis, DIEFFENBACH, Anat. u. Syst. Studien, 1885, p. 98 (in part.). 



Definition. Dorsal setae bundles with capilliform setae only, which are of two sizes, four to 

 eight in each lunette. Eyes present. 



The brief diagnosis of this species given by 0. F. MULLER would not be enough to identify 

 even the genus to which the worm belongs, did he not refer to his account of the bearded Naid 

 (die bartige Naide) published with a plate in an earlier work (2). The drawings referred to 

 indicate a Nais or a Bohemilla, more probably the former, since the much smaller eyes of the latter 

 genus would perhaps have escaped MULLER'S attention. There is, however, nothing in the figure 

 to enable one to determine with certainty the identity of this 'bartige Naide' with the species 

 subsequently called Nais barbata by TAUBER, VEJDOVSKY, and others. The only distinction between 

 the 'bearded Naid' and the 'tongueless Naid' mentioned by MULLER is the 'beard' of the former, 

 which is evidently the ventral setae of the four first setigerous segments closely crowded together 1 , 

 for MULLER says (2, p. 81) 'unter dem Kopf erscheint ein Klumpen kurzer Borsten gleich einem 

 Barte,' and is, therefore, not a distinction. Strictly speaking, the name ' barbata ' ought perhaps to 

 be dropped, and replaced by GERVAIS' 'obtusa,' but as the former name is now so well established, 

 such a change is inadvisable. 



This species has been greatly confused with the nearly allied 0. elinguis. D'UDEKEM 

 distinguished them only by the presence or absence of the glandular ventricle. This, 

 however, is no difference ; the structure in question appears to be present in both 2 . 

 TAUBER (p. 73) first indicated the only real difference between the two species 



1 DIEFFENBACH (p. 104) evidently did not so interpret the structure in question when he wrote 'eine 

 Nais barbata . . . mit besonderen klcincn Haaron am Munde, habe ich nie finden kOnnen.' VAILLANT'S figure 

 (6, PI. xxii. fig. 14), by exaggerating the tactile hairs of the prostomium, might lead to the inference that 

 these were the ' beard.' 



2 VEJDOVSKY, at least, does not refer to its absence in 0. barbata; but DIEFFENBACH says it is occasionally 

 absent in his N. elinguis ( = 0. etinguis+ 0. barbala}. 



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