The Anatomy of Megascolides Australia, 1G5 



The body varies in length from three to six feet, or even 

 longer, and contains upwards of 500 segments. Anteriorly, 

 it is somewhat swollen and hard, due to the very strong 

 septa internally. The anterior segments contain from two 

 to four annuli, which are often incomplete and slightly 

 irregular. The segment boundaries are clearly marked, and 

 posteriorly to about the 18th segment each one shows in the 

 median dorsal line a large " dorsal pore," through which, in 

 contraction of the body, the coelomic fluid is pressed out in 

 little jets. In the middle and posterior regions of the body 

 the septa are inserted into the body- wall somewhat anteriorly 

 to the line bounding the segment externally. Segments 13 

 to 20 are usually of a dark purple colour, are provided with 

 an especially strong development of nephridia, and have 

 externally to the muscle layers a strongly-marked develop- 

 ment of glands. Ventrally, a portion which, as described 

 by Professor M'Coy, is evidently equivalent to the cingulum 

 of other worms, is found on the 17th, 18th, and 19th 

 segments, where it forms three white prominent ridges, in 

 the middle one of which are the male apertures. The whole 

 of this region is called clitellum by Mr. Fletcher. 



The setse are an-anged in four pairs in each segment, but 

 cannot be seen in front of the 13th segment. 



The paired external openings of the receptacula seminis 

 lie between the 8th and 9th and the 9th and 10th segments, 

 the oviduct openings close to one another ventrally on the 

 14th segment, and the male on two small papiUee in the 

 part of the cingulum on the 18th segment, and correspond in 

 position to the internal two pairs of setae, which here cannot 

 be seen macroscopically. No nephridio-pores can be detected. 



Septa. 



The first clear septum bounds anteriorly the fifth segment. 

 Posteriorly, as far as the 16th segment, the septa are very 

 thick, strong, concave anteriorly, and bound to one another 

 by numerous connecting strands of muscle. Behind this 

 they become membraneous until the hinder end of the body 

 is reached, where they become again more muscular and 

 have very . definite supporting strands, radiating from the 

 walls of the alimentary canal. This strong anterior and 

 posterior development gives the worm great power of rapid 

 swelling of its body so as to become very tightly jammed 



