TERRICOLAE. 509 



Vermiculus Goodrich, marine, Weymouth ; Embolocephalus Randolph, Lakes of 

 Geneva and Zurich ; Phreodrilus Bedd., subterranean water, N. Zeal. 



Fam. 4. Naididae. Small aquatic worms. Setae usually in four groups 

 upon each segment sigmoid, bifurcate, hastiform, and capilliform. In most 

 genera the dorsal setae are absent from a variable number of the anterior 

 segments. Sexual reproduction at fixed intervals, between which asexual 

 reproduction by fission occurs. Sexual organs (only known in a few types) 

 far forward, commencing even in the 5th segment. Testes in 5, ovaries in 6. 

 There is sometimes only one ncphridium in a segment, and in Uncinais littoralis 

 they are said to be absent altogether. Nais 0. F. Mliller (including Slavina 

 Vejd. ; Stylaria Lamk., etc.), the first 5 segments lack dorsal setae ; N. lacustris 

 L. ; Pristina Ehrbg. (incl. Naidium Schm.); Eipistes Duj. ; Uncinais Lev.; 

 Bohemilla Vejd. ; Dero Oken, gills as processes surrounding the anus ; D. 

 Mulleri, Gt. Brit. ; Chaetobranchus Bourne, gills as hollow processes of body- 

 wall enclosing the dorsal setae, Madras ; Amphichaeta Tauber, several segments 

 without setae ; Chaetogasler v. Baer, ventral setae only present, uncinate, some 

 segments without setae, ventral ganglia more numerous than apparent segments, 

 as also in Vetrovermis Imhof., which is probably allied here. 



Fam. 5. Enchytraeidae. Small worms ; setae (absent in Anachaeta) short, 

 straight or curved, not bifid. A single pair of calciferous glands sometimes 

 present. Dorsal vessel present only anteriorly, sometimes with cardiac body. 

 Testes in 11, male pores in 12 ; a reduced spermiducal gland present ; oviducts 

 represented by pores. Spermathecae one pair, in 5, generally opening into gut.* 

 In most there is a single pore on the prestomium. Dorsal pores occasionally 

 present. Fresh-water, marine, damp earth, littoral. In the presence of calciferous 

 glands and in the distance between the spermathecae and the male pores this 

 family approaches the Terricolae. The presence of dorsal pores in some genera 

 (Fridericia) points in same direction. Distichopus Verrill; Chirodrilus Verrill ; 

 Mesenchytraeus Eisen ; Stercutus Michaels., in manure, lumen of al. canal 

 sometimes obliterated; Pachydrilus Clap.; Marionia Michaels.; Buchhohia 

 Michaels. ; Enchytraeus Henle, setae hooked at free extremity ; Fridericia 

 Michaels. ; Henlea Michaels. ; Anachaeta Vejd. (Achaeta Vejd. ), setae absent, 

 represented by large cells ; Bryodrilus Ude ; Parenchytraeus Hesse. 



The Discodrilidaef are allied here ; they are small parasitic forms, without 

 setae, with a small number of segments ; cephalic lobe divided into two ; a 

 sucker at the hind end. Pharynx with two jaws, one above the other, formerly 

 mistaken for Leeches. Branchiobdella Odier (Astacobdella Villot), parasitic on 

 gills of the Crayfish ; Bdellodrilus Moore ; Myzobdella Leidy. 



Sub-order 2. Terricolae. 



Earthworms. Oligochaeta with a clitellum which never commences 

 before the twelfth segment (except in Moniligastridae), and always 

 consists of two layers of cells. The sperm-ducts traverse two or 

 more segments on their way to the exterior. Ova small and with 

 little yolk ; egg-sacs small. Spermiducal glands, when present, have 

 not a muscular layer interposed between the inner epithelium and 



* Found also in Ehynchelmis and Sutroa. 



t J. P. Moore, Journ. Morph., 10, 1895, p. 497. 



