1887 .] Mr Frank E. Beddard on Earthworms. 157 
I described two species of Acantliodrilus — A. novce-zelandice and 
A. dissimilis — very closely allied in structure, and agreeing in a 
number of points to differ from the third species, A. multiporus. A. 
dissimilis is distinguished from A. novce-zelandice mainly by the 
character of the sperm athecae ; these organs are present in both 
species to the number of two pairs. In A. novce-zelandioe each 
spermatheca, which is somewhat pear-shaped, is provided with a 
number of small diverticula arranged round its external orifice ; in 
A. dissimilis , the spermatheca has but a single pair of diverticula, 
which are of very considerable size. The former species is also fre- 
quently provided with a double dorsal blood-vessel ; this character 
is, however, not absolutely distinctive of A. novce-zelandice ; some 
individuals agree with A. dissimilis in possessing a single dorsal 
vessel. I may state that the condition of the dorsal vessel is no 
criterion of the age of the individual. In the largest specimens of 
A. novce-zelandice dissected by me the dorsal vessel was double, 
while those specimens in which it was represented by a single tube 
happened to be very small. 
On again looking through the collection of New Zealand earth- 
worms which Prof. T. J. Parker kindly sent me, I find that I 
have confounded two apparently distinct species under the name 
of Acantliodrilus dissimilis. 
As there are a large number of individuals of A. dissimilis which 
fall into two series, I think that I am justified in making a specific, 
or at least a subspecific distinction, although the point wherein the 
two series of individuals differ is after all rather a small one ; but 
it seems to me that a differential character, if it be constant for 
a large number of specimens, is of importance, however small. 
The accompanying drawings illustrate the difference to which I 
refer. 
In fig. 1, which represents the anterior segments of the body seen 
ventrally, there are a pair of genital papillae situated on segment 10. 
For this variety I shall retain the name A. dissimilis . In fig. 2 
the genital papillae occupy a different position ; they are situated on 
the 8th segment. For this variety I propose the name of A. neglectus. 
Neodrilus monocystis, nov. gen. et sp. 
On looking over a collection of earthworms which I have received 
