MEGASCOLECIDAE 273 



Microscolex aquarumdulcium (Bedd.) (Fig. i a, b). 



Acanthodrihis georgianus (part.), Beddard, 1890, Quart. Jourti. Micr. Sci., N.S., xxx, 4, 



p. 421. 



A. aquarum-didcium , Beddard, 1893, Proc. Zool. Soc. London, 1892, p. 680. 



Notiodrilus aquarumdulcium, Michaelsen, 1899, Ergeb. Hamb. Magalh. Sammelr., Terricolen 

 (Nachtrag), p. 5. Hamburg. 



TV. aquarumdulcium, Michaelsen, 1900, Das Tierreich, x, Oligochaeta, p. 138. 



Microscolex aquarumdulcium, Michaelsen, 1907, Die Fauna SUdwest-Australiens, i, 2, p. 143. 

 Jena. 



? M. anderssoni, Michaelsen, 1905, Wiss. Ergeb. d. Schived. Siidpolar-Exp . 1901-3, v, 3, p. 8. 

 Stockholm. 



Teal Inlet, Falkland Islands, 5. iii. 27; four clitellate and one immature specimen. 



External characters. Length of clitellate specimens, 84-108 mm. ; maximum diameter, 

 2-2-5 '^''"^- Colour pallid, unpigmented. 



Prostomium epilobic, with or without a transverse furrow. Clitellum §13-16 

 dorsally, extending laterally to setal line a. Copulatory papillae variously placed, paired 

 or single, lateral or ventral papillae on segments 15-20; or at the intersegments in this 

 region. Dorsal pores absent. Nephridial pores in or very slightly below setal line c on 

 the anterior borders of the segments. Spermathecal pores, two pairs at intersegments 

 7/8 and 8/9 in setal line b. Female pores, one pair on segment 14, in front of and very 

 slightly external to the ventral setae {ad) on each side. Prostatic pores, two pairs on 

 segments 17 and 19, on small papillae situated at the ends of the seminal grooves some- 

 what external to setal line b on each side. Male pores, one pair on segment 18, just 

 external to seta b on each side and lying in the seminal grooves. Seminal grooves 

 straight and very deep, between swollen walls. Intersetal distances, aa : ab : be : cd : dd = 

 at the anterior end, approximately i\: 1 : i\: i\: 2\, dd = ^ u; zt the posterior end, 

 i\ : 1 : i\ : i\ : 2, dd = '^ u. 



Internal characters. Gizzard very reduced, in segment 5. Salivary glands extend back 

 dorsally into segment 6 or 7. Intestine commences in segment 16; typhlosole absent. 

 Lateral hearts, three pairs in segments 10-12. Nephridia with large terminal vesicles. 

 Septal organs present as in M.falclandiciis, from about septum 24/25 on, sometimes very 

 reduced and sometimes projecting forwards instead of backwards. Testes and spermi- 

 ducal funnels, two pairs, free, in segments 10 and 11. Seminal vesicles, two pairs in 

 segments 11 and 12, depending from septa 10/ 11 and 11/12 respectively, lobulate. 

 Ovaries, one pair in segment 13, fan-shaped, many-fingered. Ovisacs present in segment 

 14 from septum 13/14. 



Prostates occupying 6 to 9 segments each, of which the duct usually occupies the 

 first two, occasionally only the first. The gland is more or less straight or irregularly bent ; 

 near the gland the first third of the duct is thin and coiled once or twice ; the remaining 

 two-thirds of the duct is thick, muscular, and curved in the form of a semicircle. There 

 are normally two pairs of well-developed prostates ; in one specimen the left anterior 

 prostate is very much reduced, and penial or ventral sigmoid setae are missing. In a 



