182 COMPARATIVE ANATOMY CHAP. 



or other appendages, which generally stand on the parapodia. Sexes mostly separate. 

 Development with metamorphosis. Marine. 



A. Sedentaria = Capitibranchiata (Tubicolous worms). Pharynx (proboscis) 

 mostly non-protrusible ; without jaws. Eyes wanting, or small but numerous 

 in the head. Parapodia slightly developed, the upper with hair-like setae ; the 

 lower are transverse swellings with hooked sette. Gills chiefly on the anterior 

 segments, or limited to the head. Live in various kinds of tubes. Fam. Cirratulidoe : 

 Cirratulus. Fam. Arenicolidce: Arenicola. Fam. Spionidce: Spio. Fam. Arididce : 

 Aricia. Fam. CMorhccmidce : Siphonostoma. f&m.. Terebcllidoe : Lanice (Terebella) , 

 Pohjmnia, AmpMtrile. Fam. Serpulidce : Serpula, Sabella, Spirographis, Myxicola, 

 Protula. Fam. Hcrmellidce : Sabcllaria (Fig. 147, p. 221). Fam. Sternaspidce : 

 Sternaspis, 



B. Errantia = Dorsobranchiata (carnivorous Annelids). Pharynx protrusible, 

 mostly with jaws ; head distinct, mostly with a few large eyes. Parapodia well 

 developed. Gills generally on the dorsal parapodia. Free-swimming or creeping 

 animals, many of which live, at any rate at certain times, in tubes of their own 

 making. Fam. Aphroditca : Aphrodite, Hermione, Polynoc. Fam. Amphinmnidoe : 

 Amphinomc, Euplirosyne, Notopygos. Fam. Eunicida; : Diopatra, Eunice (Fig. 124, 

 p. 188), Halla. Fam. Nereidcc : Nereis, Neplithys. Fain. Glyceridcc : Glycera. Fam. 

 Syllidcc : Raplosyllis, Syllis, Exogone, Autolytus, Myrianida. Fam. Hesionidoe : 

 Hcsionc. Fam. Phyllodocidce : Phyllodocc. Fam. Alciopidce: Alciope, Asterope. 

 Fam. TomopteridcK : Tomojrtcris. 



Sub-Order 3. Echiuridse. 



Body tubular, in adult condition unsegmented or indistinctly segmented, 

 without parapodia, without cirri, without gills. In front, on the ventral side, 2 

 hooked setfe. In the terminal portion of the much-coiled intestine 2 anal glands 

 enter (modified nephridia of the anal region), which may be considered as excretory 

 organs. There -are besides 2 or 3 pairs of nephridia, or only one nephridium. 

 Anterior end of the body over the mouth produced into a long variously shaped 

 mobile prostomium (cephalic lobe) with ventral furrow. With blood-vascular system. 

 Sexes separate. Development with metamorphosis. Marine animals with unknown 

 mode of life. EcMurus (Fig. 148, p. 223), Thalasscma, Bondlia. The diminutive 

 Turbellaria-like ciliated males of this last species live parasitically in the females. 



Order 3. Myzostomidae. 



Body flat, disc-shaped, externally unsegmented. Margin of the body with cirrus- 

 or wart-like processes. On the ventral side, in two longitudinal rows, 5 pairs of 

 parapodia, with hooks and supporting rod. In addition to the parapodia, on each side 

 4 suckers. Pharynx as in the Rhynchobdcllidce among the Hirudinea. Intestine 

 with branched lateral diverticula. Body cavity reduced. Circulatory, excretory, and 

 respiratory organs wanting. The nervous system consists of the cesophageal ring, 

 and of a ventral chord fused into a ventral ganglionic mass. The brain is reduced. 

 Hermaphrodites. The oviducts and the intestine together enter a cloaca. The 

 seminal ducts have two separate external apertures on the ventral side. Besides 

 hermaphrodite individuals, there are, in certain species, small males (complementary 

 males). Parasitic on Crinoids (Fig. 175, p. 262). 



CLASS IV. Prosopygia. 



Body naked or shelled, varying greatly in form. Round the mouth a circle of 

 ciliated tenacles, which are often inserted on a common horseshoe-shaped tentacle- 



