508 ANNELIDA. 



are continually bringing up to the surface some of the deeper soil, 

 and depositing it in the form of casts; they thus assist in turning- 

 over the soil, and in mixing together the different parts of it, and 

 the soil of the deeper layers is thus exposed to the atmosphere. 

 Phosphorescent earthworms have been observed, but they are not 

 common. 



Sub-order 1. Limicolae. 



Oligocliaeta with a clitellum commencing not later than the tenth 

 or eleventh segment, and consisting only of a single layer of cells ; 

 the sperm-ducts only occupy two segments, the external pore being 

 on the segment following that into which the funnel opens ; the 

 male pore is situated in front of the female pore; eggs generally 

 large, always provided with abundant yolk ; egg-sacs large ; spermi- 

 ducal glands, when present, possess a muscular layer interposed 

 between^ the inner epithelium and the glandular layer; sexual 

 maturity at a fixed period. For the most part fresh-water forms. 



Fain. 1. Phreoryctidae. Aquatic or terrestrial, of slender form, often very 

 long. Setae in four rows of single setae or of couples, sigmoid. Testes in 10 

 and 11. Ovaries in 12 and 13, or in 13 only. Sperm-ducts, two pairs opening 

 separately, without spermiducal glands. Spermathecae in front of testes, 

 without diverticula. No genital setae. Phreoryctes Hoffmeister, Eur. , N. Am. , 

 N. Z., clitellum 11-14, 4 ovaries; Pelodrilus Beddard, New Zealand, clitellum 

 11-13. 



Fam. 2. Lumbriculidae. Aquatic worms of moderate size. Setae paired and 

 /-shaped, sometimes with the free extremity bifid. The dorsal blood vessel or 

 the transverse vessels with blind contractile appendages (except Stylodrilus and 

 (l)AUuroides). Testes in 9 and 10; ovaries in 11. Two pairs of sperm-ducts 

 (exc. Alluroides) uniting to open by a single spermidueal gland on each side, 

 which lies in front of the oviducal pores usually in 10. Lumbriculus Gr., 

 male pore in 8 ; Rhynchelmis Hoffmeister ; Trichodrilus Clap. ; Phreatothrix 

 Vejd. ; Claparedilla Vejd. ; Stylodrilus Clap. ; Sutroa Eisen ; Alluroides Bed., 

 this genus presents certaiu characteristics of Terricolae. Eclipidrilus Eisen. 



Fam. 3. Tubificidae. Aquatic, fresh-water or marine, of small size and 

 slender build. Setae of three kinds capilliform, pectinate, and uncinate of 

 which the first two (when present) are only found in the dorsal bundles. Dorsal 

 and ventral blood vessels connected in every segment. Testes in 10, ovaries in 

 11, sperm-ducts always ending in spermiducal gland opening on 11. Oviducts 

 open between 11 and 12. Spermathecae one pair in 10. Tub if ex Lam., dorsal 

 bundles with capilliform, pectinate, and uncinate setae ; Clitellio Sav. ; Cl. 

 arenarius Sav., coasts of Europe; Limnodrilus Clap., with uncinate setae 

 only, Eur. and California; Hcsperodrilus Bedd., Falkland Isl. and S. Am.; 

 Hetcrocliaeta Clap., marine, coasts Engl. and Belg. ; Peloscolcx Leidy, N. 

 Am. : Psammoryctcs Vejd., setae capillif., unc., palmate, and pectinate, Eur. ; 

 Hemitubifex Eis. ; Telmatodrilus Eis. ; Spirospcrma Eis. ; Ilyodrilus Eis. ; 

 Bothrioneuron Stole; Lopliochacta Stole; Brancliiura Bedd., with median 

 dorsal and ventral gills, Victoria regia tank in Regent's Park, London ; 



