DEVELOPMENT OF ACANTHODRILUS MULTIPORUS. 525 
distinct ducts running side by side in Megascolides.” 
Another objection urged by Mr. Spencer is one which I also 
urged myself; it is that in Pericheta, which has a primitive 
excretory system, the genital ducts are fully as specialised as 
in other types where the nephridia are greatly modified. He 
concludes that in all Terricole the genital ducts have no con- 
nection with the nephridia, and are not to be regarded as 
nephridia specially modified to serve the purpose of conveying 
genital products to the exterior. 
M. Perrier had found that in Anteus the sperm-ducts are 
actually represented by nephridia, a condition analogous to 
that of Hiolosomato be mentioned immediately. Butin view 
of the possibility that in Anteus the sperm-ducts run em- 
bedded in the body-wall as in Acanthodrilus, and may 
therefore have been invisible on dissection only, it must be 
considered that this instance requires further study before the 
facts can be definitely accepted as a contribution to the ques- 
tion of the homologies between genital ducts and nephridia. 
Besides, in Rhinodrilus, which comes extremely close to 
Anteus, if it be not actually congeneric, vasa deferentia of the 
ordinary type are unquestionably present. 
An important contribution to the question of the homolo- 
gies of the genital duct with the nephridia is contained in a 
memoir upon the genital organs of Aolosoma by Dr. Stole 
(23). As Dr. Stole has favoured me with an English abstract 
of his paper I give a fairly full account of it, as there must be 
comparatively few persons who can read the original. 
The testis is situated in the 5th segment, the ovary in 
the 6th; the gonads appear to be unpaired, and are situated 
between the ventral blood-vessel and the ventral body-wall. 
The spermathece vary in number from one pair to three, 
and are in Segments 3, 4, and 5. There is a tendency for 
only one spermatheca in each of these segments to be deve- 
loped. The clitellum is developed only on the ventral side 
of the sexual segments. On the median ventral surface of the 
6th segment is the unpaired oviducal pore; as a pair of 
nephridia also exist in this segment, it is not plain that the 
