APHRODITA. 79 



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

 the shores, live for by 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 with 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 Annelida, 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 commensals and 

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

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

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

 Annelida, 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 Triceratia HaswelJ. 



aa. With only a median tentacle. 



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



setae; ventral setae with bifid tips A-phrogenin Kinberg. 



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

 c. Eyes pedunculate. 



d. Hairs of notopodium in part arrow-formed; dorsal felting loose and often incomplete. 

 e. Neuropodial setae with the. tips bifid, distal region not pectinate. . . .Laetmonice Kinberp;. 

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



prone, dense Pontocjada Claparede. 



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

 with many fasciae of irised hairs Apkrodiia Linne. 



Aphrodita Linne. 



Linne, Syst. nat., ed. 10, 1758, 1, p. 655; McIntosh, British annelids, 1900, 1, pt. 2, p. 24L 

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

 Milnesia Quatrefages, Hist. nat. annel^s, 1865, 1, p. 211 (min. ad part. M. borealis). 

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



* For a detailed account of both external and internal parasites in the several groups of Aphrodi- 

 toicea see G. Darboux, Recherches sur Ics aphroditiens. Bull. sci. France & Belgique, 1900, 30, |). 18 

 et seq. 



