NEPTHYS. 93 



seen from above, less commonly quadrangular or hexagonal. Normally there 

 are fom* tentacles, two borne on the anterior margin on each side, or in rare 

 cases, only two tentacles are present. Eyes two in number and small, or absent. 



Peristomial somite normally fused with the second one. 



Parapodia biramous, the branches widely separated from each other and 

 each provided with a special membranous lobe or lamella more or less strongly 

 developed; and in connection with it often other processes. In addition the 

 notopodium bears a small notocirrus and a branclna, and the neuropodium bears 

 a neurocirrus and may or may not bear also a branchia. 



Each branch of the parapodia bears a stout aciculum. The setae are all 

 simple, or rarely composite setae may occur in the neuropodia. The setae are 

 mostly strongly cross-striate or camerated, while some are serrated and some 

 have lyriform tips. 



Anal cirri usually one, rarely two. 



Proboscis showing two regions; ^\ath or without two short horny jaws; 

 a double row of bifid papillae around the aperture and with or rarely without 

 papillae in longitudinal series (14-22). 



The members of this family are \agorous animals with a strong muscular 

 development. They hve most abundantly in or near the Uttoral region though 

 they areoccasionaUy taken from considerable depths {e.g. Nepthys phyllobranchia 

 Mcintosh from 1,240 fathoms). They frequent sandy bottoms or sand more or 

 less mixed with slime or mud in which they biuy themselves with sin-prising 

 rapidity, using the proboscis in forming the burrow (Cf. Gravier, Nouv. arch. 

 Mus. hist, nat., 1901, ser. 4, 3, p. 126). In their aUmentary tracts Gravier 

 found such forms as diatoms, radiolarians, sponges, Foraminifera, and the 

 remains of other polychaetes which their characteristically strong general mus- 

 culature and their powerful probosces enable them to overcome. 



The family is remarkably homogeneous, only a single genus being recognized 

 by most authors though various other groups have been proposed as indicated 

 by the synonomy given below under Nepthys. 



Nepthys Cuvier. 



RIgne Anim., 1817, 13, p. 203; Savignt, Descript. Egypte. Hist, nat., 1809 [ = 1822], 1, pt. 3, Audouin 



& Milne Edwaeds, Hist. nat. litt. France. Ann61ides, 1834, 2, p. 232. 

 Diplobranchus Quatrefages, Hist. nat. anneles, 1865, 1, p. 433. 

 Portelia Quatrefages, Op. cit., 1865, 1, p. 431. 



Aglaophamus Kiptoerg, Ofvers. K. vet. akad. Forh., 1865, no. 4, p. 239. 

 Aglaopheme Kinberg, Ihid., p. 240. 



