APHRODITA. 79 



The aphroditids, while occurring to some extent in the shallow water along 

 the shores, live for hj far the most part at greater depths. The Albatross 

 dredged Laetmonice wyvillei from the excessive depth of 3,120 fathoms. Both 

 the bathymetrical and the geographical range \vith certain species is very great. 

 Another species of Laetmonice, L. benthaliana Mcintosh, has been taken at only 

 twenty-six fathoms on the one hand, and on the other, at 2,900 fathoms (Chal- 

 lenger AnneUda, 1885, p. 40, 45). The geographical range of Laetmonice pro- 

 ductor is enormous. Some forms burrow in the mud, a process in which the 

 spines seem to be instrumental. This habit accounts for the fact that the setae 

 and elytra of certain species are commonly found coated with mud. The 

 aphroditids are sluggish in movement. They often occur as conmiensals and 

 give support to a great variety of external parasites such as other annelids, pro- 

 tozoans, sponges, coelenterates, ecliinoderms, bryozoans, crustaceans, and tuni- 

 cates.^ Thus, in speaking of Laetmonice productor Mcintosh (Challenger 

 AnneUda, 1885, p. 43) says: — "A large number of parasitic growths — sponges, 

 Foraminifera, diatoms, hydroid zoophytes, Polyzoa, Loxosomae, ascidians, en- 

 tangled worms, and others in tubes of sponge-spicules — occur amongst the 

 bristles." All are carnivorous, and eat a great variety of animals, including 

 other aphroditids and annelids in general. 



Key to Genera. 



a. Lateral tentacles as well as a median one present : Triceraiia Haswell. 



aa. With only a median tentacle. 



b. Eyes implanted on base of antenna; dorsal hairs not felted over the eljlra; no arrow-shaped 



setae; ventral setae with bifid tips Aphrogenin Kinberg. 



bb. Eyes not on base of antenna; dorsal hair more or less felted. 

 c. Eyes pedunculate. 



d. Hairs of notopodiuin in part arrfiw-formed ; dorsal felting loose and often incomplete, 

 e. Ncuropodial setae with the. tips bifid, distal region not pectinate. . . .Laetmonice Kinberg. 

 dd. Notopodial setae simply serrate along convex side or smooth, but never arrow formed, long, 



prone, dense Ponlogcnia Claparede. 



cc. Eyes sessile; dorsal felting very dense, irregularly pierced by large brown hairs; parapodia 

 with many fasciae of irised hairs Aphrodita Linn6. 



Aphrodita Linne. 



Linnd, Syst. nat., ed. 10, 1758, 1, p. 655; McIntosh, British annelids, 1900, 1, pt. 2, p. 241. 

 Halithea Savigny, Descript. Egj-pte. Hist, nat., 1809 [= 1822], 1, pt. 3, p. 11, 18. 

 Milnesia Quatrefages, Hist. nat. anneles, 1865, 1, p. 211 (min. ad part. M . horealis). 

 Aphroditella Roule, Bull. Mus. hist, nat., 1898, 4, p. 191. 



' For a detailed account of both external and internal parasites in the several groujis of Aphrodi- 

 toicea see G. Darboux, Recherches sur les aphroditiens. Bull. sci. France & Belgique, 1900, 30, p. IS 

 et seq. 



