POLYCH2ETA, EHRANTIA. 379 



tubes on the parapodia (Dorsibranchiata). The Errantia are pre- 

 datory in their habits (Rapacia) and swini freely in the sea; but 

 they may also inhabit temporarily thin membranous tubes. 



Fam. Aphroditidae. Broad scales (elytra) on the notopodia. These are 

 usually placed on alternate segments, often only on the anterior part of the 

 body. Praestomium, with eyes, with one unpaired and usually two lateral 

 tentacles, to which may be added two stronger lateral ventrally placed tentacles 

 (palps). Proboscis cylindrical, protrusible, with two upper and two under 

 jaws. Aphrodite aculcata Lin. (Hystrix marina Redi.) The back has a thick 

 felt of hairs. Eyes sessile. Numerous setce on the ncuropodia. Polyno'd 

 scolopendrina, Sav. Ocean and Mediterranean. 



Fam. Eunicidse. Body very long, composed of numerous segments. Prresto- 

 rniuin with several tentacles. Parapodia usually uniramous, rarely biramous, 

 usually with ventral and dorsal cirri as well as branchins. One upper jaw 

 composed of several pieces, and a lower consisting of two plates ; both lie in 

 a sac, the jaw-sack, on the dorsal surface of which runs the pharyngeal tube. 

 Staurocephalus vittatus Gr., Hallo, (Lysidice) partlienopcm Delle Ch., Naples. 

 Diopatra ncapolitana Delle Ch., Naples. Eunice Ifarassii And. Edw. 



Fam. N ereidae = Lycor id 'cc* The elongated body is composed of numerous 

 segments. The pnestomium has two tentacles, two palps, and four eyes. The 

 parapodia are either uni- or bi-ramous, and are furnished with dorsal and ventral 

 cirri and with composite sete. Proboscis usually possesses spines, and always 

 two jaws. Nereis Dumcrilii Aud. Edw., French and English coasts, to which 

 belongs Heteronereis fucicula, Oerst. N. cultrlfcra Gr., Mediterranean N. 

 fucata Sav., North Sea. The form formerly distinguished as Heteronereis 

 Oerst. differs from Nereis in the great size of the pra3stomium and of the eyes, 

 also in the extraordinary development of the parapodia, and in the abnormal 

 formation of the hinder end of the body. It belongs, however, to the same 

 cycle of development as Nereis and Wereilejias. 



Fam. Glyceridae. Body slender, composed of numerous ringed segments. 

 The prrcstomium is conical and. ringed, with four small tentacles at its point 

 and two palps at its base. The proboscis can be protruded to a great length, 

 and is provided with four strong teeth. The hremal fluid, coloured by red 

 corpuscles, is contained in the body cavity and the branchial sinuses. There 

 is no special vascular system. Glycera capitata Oerst., North Sea. 



Fain. Syllidse. Body elongated and flattened, head usually with three 

 tentacles and two to four tentacular cirri. The protrusible proboscis consists 

 of a short proboscis tube, a pharyngeal tube lined by stiff cuticular formations, 

 and a portion characterised by annular rows of points. Sexual and asexual 

 individuals, differing in form, are sometimes found in the same species. Many 

 carry their eggs about with them until the young are hatched. Fi/llix /-if tain 

 Gr., Mediterranean. Odontosyllis gilba Clap., Normandy, Autolyius proTifi / 

 0. Fr. Mull., asexual form. The male has been described as Polyloxtrichus 

 Mutter i Kef., the female as Sacconereis hclyolandica Mull, ^ilit/'roilnrum 

 peripatiis Gr., Mediterranean. 



Fam. Alciopidse (Alciopea). With two large hemispherical projecting eyes. 

 Ventral and dorsal cirri leaf-like. The proboscis is protrusible, the tube of 

 the proboscis being thin walled and its terminal portion thick walled. At 



* Compare E. Grube, " Die Familieder Lycoridcen," JaJircsber. der Sehlesis- 

 GesdUcliaft, 1873. 



