16 E. RAY LANKESTER, ON THE 
See cicine aE et 
I I I PS habe |e 
| a 
| | | | 
Tubifex Bonneti, Clap. ..........., | da}sisleapa) Sea gene SiS jock. MC ae es 
Limnodrilus Udekemianus, Clap. |...|...|... ee, oe S|s R} C| ... |S |&e. 
A Hoffmeisteri, Olap.|...|...|...)...]... J... Sis Ri C| ... |Si&e. 
Lumbriculus variegatus, Grube...)...)...).....)..).0. S]...| BR} CG OF Si&e: 
Stylodrilus Heringianus, Clap....|...\...|...|...)e..|o0 Si] Boye) 1Ogsi&e 
Trichodrilus Allobrogum, Clap...)...!...)...)c0.(...[es. $|S|(0?)) CleR| R|S 
Enchytraus vermiculus, Hoffm. |...)...|...|... Ri....8{/S| S |S} S |C(o)|S j&e. 
Gegenbaur, describing the ciliated canals of Lumbricus 
and Scenuris, stated that M. D’Udekem, in considering that 
the segment organs were wanting in the generative segments 
of Tubifex, was wrong, and that the efferent canals which he 
described were only enlarged segment organs. Dr. Williams, 
of Swansea, soon after this, made known his views, which are 
embodied in a paper in the ‘ Philosophical Transactions’ for 
1858. He certainly has the credit of having appreciated the 
fact that the segment organs in the Limicole are in certain 
segments developed into efferent canals of the reproductive 
system; but in attempting to go beyond this that author 
has been led into many errors and inaccuracies, and his 
paper has been well-styled by Claparéde “un échafaudage au- 
dacieux et peu solid.’ He attempted to show that not only 
were the efferent canals modifications of the segment organs, 
but that the essential glands, the ovary and testis, were 
developed from them—a proposition which jars against all 
homologies of the reproductive organs, from the protozoa 
upwards. ‘To further his view, Dr. Williams published a most 
remarkable account of the genitalia of the earthworm, and de- 
preciated the accurate observations of Hering and D’Udekem ; 
alternating testes and ovaries of large size were discovered 
with conspicuous apertures externally, whilst the real ovaries, 
the oviducts, spermatic reservoirs, and efferent canals, were 
entirely ignored, and their existence denied. Ishould not have 
thus emphatically exposed Dr. Wilhams’s inaccuracies had 
not his statements and views been largely quoted and ap- 
proved in a book of extensive circulation, viz., ‘ Rymer Jones’ 
Animal Kingdom,’ a work which is much read and consulted 
by students of comparative anatomy. 
Seeing, then, that the segment organs are deficient in the 
segments containing the oviduct, sperm reservoirs, and efferent 
canals, amongst the Limicole, and considering that in 
structure they are all very similar in this group, it is 
concluded that the oviducts, sperm-reservoirs, and effer- 
ent canals, are the modifications of the segment organs ; 
the essential organs, of course, having nothing to do 
