158 Proceedings of Royal Society of Edinburgh. [april 4, 
from New Zealand by the kindness of Prof. T. J. Parker, I found 
a single individual which differs from the rest in a number of 
characters. The remaining specimens belong to three distinct new 
species which I have lately described,* referring them to the genus 
Acanthodrilus . The specimen which forms the subject of the 
present communication appeared at first sight to belong to the 
species Acanthodrilus dissimilis , F. E. B. , though considerably more 
slender than any of the individuals of that species which the 
collection contained. 
The setse are disposed in four series of pairs, and the nephridial 
pores alternate in position precisely as in Acanthodrilus dissimilis. 
The elitellum occupies a similar position, and extends over an equal 
number of segments, viz., 5 (13-17),, Instead of there being two 
pairs of spermathecal apertures, there is only a single one situated 
between the 7fch and 8th segments, on a line with the inferior pair 
of setse. The male generative pore is placed upon the 17th segment, 
and each pore is continuous with a groove upon the integument, 
which extends over the following segment, and ends upon the 
middle of the 19th segment. I could not, however, detect a second 
pair of male generative pores upon this segment. In Acanthodrilus 
dissimilis — at least in many individuals — there is a similar groove 
connecting the genital pores of the 17th with those of the 19 th 
segment entirely similar to that of Neodrilus. It is possible that 
this supposed new genus Neodrilus is really an Acanthodrilus , in 
which the posterior pair of male generative pores, together with 
their glands, have not yet been developed. I am not aware, how- 
ever, of any similar instance in the genus Acanthodrilus , and the 
present species is fully mature. In favour of this supposition, how- 
ever, is the condition of certain other peculiar accessory generative 
structures which I have lately described t in a species of Acantho- 
drilus from New Caledonia ; these are sometimes present and some- 
times absent in mature individuals. Another possibility is that the 
present individual is abnormal, and it is principally for these reasons 
that I have hesitated in making a new genus ; though there can be 
no doubt of the specific distinctness of the worm. 
The male generative pore is continuous with a long, coiled, 
tubular prostatic gland, the proximal region of which is a slender 
* Proc. Zool. Soc., 1885, pt. iv. t Proc. Zool. Soc., 1886. 
