Zoology.] NATUKAL HISTORY OF VICTORIA. [Annelida. 



Plate 7. 



MEGASCOLIDES AUSTEALIS (McCoy). 



The Giant Earth-worm. 



[Genus MEGASCOLIDES (McCoy). (Sub-kingd. Articulata. Class Annelida. Order 

 Abranchiata. Section Terricola. Earn. Lumbricidse.) 



Gen. Char. — Body very large, cylindrical, of from 300 to 500 rings, the anterior portion 

 from a little behind the mouth thickest, suddenly narrowing at genital rings, then for some feet 

 a little wider and again dilating slightly at the tail ; the prominent middle third of each ring 

 set with 8 very minute spinules arranged in four pairs on the abdominal and lateral two-thirds 

 of each ring, leaving rather less than one-third of the dorsal surface smooth, and forming 8 

 longitudinal lines along the body from the genital rings. A row of spiracular pores along the 

 mid-line of the back opening on the anterior edge of each of the rings except near the head in 

 front of clitellae. An imperfect genital, hard, cingulum or clitellse extending only over the 

 ventral third of about three rings towards anterior tenth of the length ; rings near posterior 

 end much narrower and less distinctly marked than at the anterior end.] 



Description. — Body of about 350 to 500 ring's (about 10 in 1 inch of anterior 

 end when extended, or 14 in same space when contracted, about 16 in same space at 

 middle of body), tapering* to each end when extended, but both anterior and posterior 

 ends becoming* club-shaped when contracted ; a marked narrowing- of the body 

 between the 36th and 40th rings behind the clitellse ; anterior end, of about the first 

 25 to 40 rings, sooty brownish-black, lighter on the ventral fourth of the surface, 

 rest of body, back, belly, and sides alike in color and of a light, brownish flesh-color 

 with a slight purplish-grey reflection ; oral and anal apertures central. Between 

 the 32nd, 33rd, and 34th rings from the mouth, on the ventral side, are three genital 

 short bands, less than the rings in thickness and only extending round about one- 

 fourth of the circumference of the body, forming an imperfect cingulum or clitellse 

 much tougher in consistence and lighter in color than the other parts. About 2 feet 

 long when contracted and about 6 feet long when extended ; 8 lines to £ of an inch 

 in diameter. Spinets or setae ^th of an inch long and ^^oth of an inch wide with 

 the exterior pointed end very slightly hooked, general form slender, nearly straight, 

 with a very slight sigmoid curve, subtruncate obliquely at base (more slender and 

 less curved than Vaillant's figure of the setae of Perichceta cingulata, Ann. des Sc. 

 Nat. v. 10, pi. 10, f. 2, or Schmarda's figures of those of the four other species, and 

 nearly agreeing with Baird's figure of Megascoleoc {Perichceta) diffringens, but rather 

 more slender) ; each seta projecting from the end of each of 8 minute conical papillae, 

 the base arising from the prominent middle ridge of each ring, and the apices 

 directed outwards and backwards ; the 8 setae, on successive rings, form 8 longitu- 

 dinal lines, beginning from the 25th to the 32nd ring, to end of the body, arranged 

 in four pairs, the outer pairs on each side about the length of a contracted ring apart, 

 the ventral pair a little farther apart, and the pairs of rows about twice as far apart 

 as the two rows of the pair ; one-third of each ring forms a smooth space along the 

 back of the animal, down the centre of which the breathing spiracles form a conspi- 

 cuous line of transversely oval pores beginning about the 40th ring, and becoming 

 indistinct before quite reaching the posterior end; the dorsal portion of the rings 

 flatter than the rest and without the longitudinal muscular plicae or wrinkles on the 

 margins of the ventral and lateral thirds. The mouth is a transverse slit when closed 

 \ of an inch wide ; but when partially open the upper edge has a hard, thickened, 



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