20 ON THE ANATOMY OF MEGASCOLIDES AUSTRALIS, 
seen in the rod. Hach rod is again surrounded by a very clearly-marked sheath of 
tissue, which in transverse section seems to consist of fine wavy fibres, arranged, as in 
the figure, in a circular manner, with nuclei here and there. 
In longitudinal sections, the rods are very clearly seen to be formed of a 
homogeneous structure, perfectly continuous alone apparently the whole body. 
The “ giant fibres” can in no way be called “neural canals,” the name suggested by 
CunnincHam* for what must be regarded as homologous structures in the Polychete. 
‘Neural canal” is a term which already has a definite meaning, and the structure to 
which this is usually applied has, of course, no connection whatever with the structure 
now under consideration. The “giant fibres” of Megascolides are remarkable (1) for 
the very definite central rod of homogeneous gelatinous material, and (2) for the equally 
definite enclosing sheath of connective tissue. No connection exists between the 
fibres and any of the nervous elements, and it seems probable, more perhaps because 
it is difficult to suggest any other use for them, than because of any direct evidence in 
its favour, that the usually accepted idea of their possessing solely a supporting 
function is the correct one. They doubtless serve also, as suggested by Cunniyeuan, “to 
prevent the nerve cords being bent at a sharp angle, causing them always to remain 
in curves, and so to escape injury during the wriggling and burrowing of the worm.” 
Under these circumstances, the name of “neurochord,” given to them by Vejdovsky, 
appears to be the most applicable. 
I hope very shortly to be able to study their development in Megascolides, in 
which in its adult state they form striking features in sections of the nerve cord. 
7.—Nephridia. The nephridia form, perhaps, the most interesting structures in 
Megascolides. During the last two or three years, our knowledge of the nephridia of 
various earth-worms has been very greatly enlarged, owing in large part to the 
descriptions of Brnnam and Brpparp. 
The arrangement of the nephridia in Megascolides has many points of agreement 
with that described by Brpparpt as obtainme in Pericheta aspergillum and 
Acanthodrilus multiporus, and has already been shortly described.{ 
The main features in connection with the system are (1) the presence of numerous 
nephiidia im each segment, (2) the modification of the nephridia in various parts of the 
body, (3) the connection of the ducts of the various nephridia. Purrinr was the first 
apparently to draw attention to the presence of several nephridia in one segment, and 
in 1885, Bepparp§ described the same occurrence as taking place in a species of 
Acanthodrilus, from New Zealand, which, according to him, had eight nephridia in 
each segment. Brnxam|| mentions the fact that in certain worms (a Pericheta from 
* Q.J.M.S., Nov. 1887, p. 267. § Proc. R.S. May 1885, p. 459. 
+ Q.J.M.S., Feb. 1888. || Q.J.M.S. Feb. 1886, p. 256. 
t Proc. R.S. Victoria. Oct. 1887. 
