222 Introduction to Animal Morphology. 



hooks ; most are tube-dwellers, buried in sand or fastened 

 to stones ; body transparent ; eyes 2 (Disoma), or none. 

 17. Nerinidae segments homonomous ; head with eyes; 

 feelers often none ; feet one- (Pygospio) or two-oared 

 (Nerine). Spio has tongue-like gills. Colobrachus has a 

 peculiar anal breathing organ. 18. Cirrhatulidze rounded, 

 fusiform ; head with no teeth, feelers, nor tentacles ; oars in 

 two series, on tin- lower hooks; thread-like gills on five or 

 six anterior segments (Dodecaceroea), or on all but the first 

 and last (Cirrhatulus). Andoninia has spindle-like blood 

 corpuscles. 19. Ariciidce with no feelers nor teeth, and 

 gun-rally four eyes; segments short; oars two-branched. 

 The epipharvnx is leaf-like in Anthostoma, protrusible in 

 Kphesia, which is eyeless, but not protrusible in the four- 

 eyril SplKLTodurum. 20. Opheliidx feelers and eyes none ; 

 xnnit. -mall, one or two only with bristles, one 



set of gills limited to tin- middle of the back (Ophelia), or on 

 ncarK jiiu-nt ,'1'ravisia) ; head pointed ; tail papillary; 



body Hat beneath, with i< >phelia) or without a definite "sole" 

 ^Annnotrypane;. Ophelia has in its perivisceral lluid stellate 

 bodies with immovable processes. 21. Arenicolickv head 

 small, conical, with no eyes nor :iul a papillary pro- 



boscis ; the middle segments have tree-like gills, while the 

 front and tail - have none; oars double, the upper 



bristled, the lower hooked ; the larva; are polytrochal ; they 

 burrow in sand. Arenicola, the " lug-bait," has no tail ap- 

 pendages. Scalibregma has anal cirri. Eumenia has gills 

 on tin- anterior segments. 



4. Cephalobranchiata mostly tube dwellers, with breath- 

 ing organs on the head, either as long contractile threads, or 

 fan-like, or spiral ; pinnate or comb-like lobes, and sometimes 

 tree-like gills on the prostomium ; some have dorsal cirri, 

 like-wise respiratory ; no teeth nor epipharynx. i. Pherusidx 



; nd peristome bristle-less ; gills of simple thr 

 surrounded by a girdle of long, yellow, thick bristles ; zonites 

 not ringed ; parapodia with upper linear and lower hook-like 

 bristles ; blood green ; body often shaggy, with sometimes 

 terminal suckers, whereby they adhere to foreign bodies 

 (Chlorcema Dujardinii is found adherent to Echini) ; intestine 



