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no jaws; septa incomplete except one strong diaphragm 
in front; anterior to this the nephridia are large and 
excretory while the posterior ones are mere funnels and 
act as genital ducts. Tubicolous or burrowing worms. 
IV. CaprrEtiiFrormia._—_No__prostomial processes; 
parapodia do not project, setze unjointed, capilliform in 
the anterior segments, hooded crotchets in the posterior 
segments (this division does not correspond to marked in- 
ternal differences), no cirri; no jaws; nephridia small and 
may be more than one pair per segment; no blood-vessels, 
but the ccelomic corpuscles are red. | Burrowers. 
V. ScoLecirorm1a.—Prostomium rarely with sensory 
processes ; peristomium without cirri; parapodia not well- 
developed, setze unjointed, no uncini present; no jaws; 
septa not regularly developed (some being absent); 
nephridia often reduced in number but all alike. 
Burrowers. 
Arenicola belongs to the last sub-order, which contains 
six families. 
(1) OpHenipa#.—Comparatively short worms, many 
of which have a pearly lustre; no prostomial processes ; 
parapodia obscure, but dorsal cirr1 often present, e.g., 
O phelia. 
(2) Matpanipa (or CiyMENID®). — Prostomium 
truncated; body formed of long and few segments, never 
provided with gills or other processes; the neuropodial 
sete are hooked crotchets, each with characteristic sub- 
rostral tuft. Inhabit sandy tubes, e.g., .V2comache, 
Aaiothea, Clymene. 
(3) ARENICOLID2#.—NSee below for definition. 
(4) ScatipreGmMip#.—Arenicoliform or maggot lke; 
gills, if present, confined to the first five segments; pro- 
stomium small and either drawn out at its lateral angles 
into short processes or bluntly rounded; parapodia con- 
