46 
in 18 and the following somites (Pl. II, Fig. 3). One specimen has a 
large nephridium.on one side of 9, and a few have fairly large nephridia 
in 15 and 16. They are regularly much smaller pr absent in 10, 11, and 
7, and in some specimens in 15 and 16. 
The brain differs somewhat in shape from that of H. emissarius and 
certain other species. The length of the median antero-posterior axis is 
about equal to the greatest lateral diameter (Pl. II, Fig.1), and the 
greatest dorso-ventral axis is about three-fourths as great. The posterior 
surface is but slightly concave, and the anterior surface is conical with 
the apex somewhat rounded. In median frontal sections of the brain, 
the anterior margins include an angle of about 90°. The peculiar 
cushions of cells which support the ventral nerve cord are, as far as 
observed, found associated with all the ganglia except the first one. Those 
related to the second and third ganglia, in somites 3 and 4, are small and 
without the lateral wing-like extensions, and the others are larger and 
- have such extensions more or less developed. No examination has been 
made of their distribution in the posterior part of the worms. 
The reproductive organs are but incompletely developed in all of 
the specimens examined, but the gonads are large and unmistakable. 
Eight sectioned specimens and nine specimens cleared in cedar oil are per- 
fectly uniform in having one pair of gonads in 10 and one pair in each 
of somites 15 and 16 (Pl. II, Fig.3). The anterior pair are doubtless 
spermaries and the other two pairs are ovaries. There are vestiges of 
spermiducal funnels and of the adjacent parts of the sperm ducts, but no 
traces of the location of the spermiducal pores. Two sectioned speci- 
mens show sufficient vestiges of the oviducal apparatus to indicate that 
the oviducal pores were in the anterior parts of 16 and 17 and dorso- 
laterad of the lines connecting the ventral setae of either side of the 
worm. One of the two specimens has an additional ovary of small size 
on one side of 17 but has no corresponding oviduct. The wide separa- 
tion of the ovaries from the Spermaries and the extreme posterior posi- 
tion of the former are characters that are very aberrant, not only for the 
genus, but for the Oligochaeta as a whole. No traces of sperm sacs, 
ovisacs, or spermathecae have been detected. 
GENERAL DrIscussION 
The marked differences in the relations of the gonads are sufficient 
to distinguish H. forbesi from H. emissarius, but it differs also in its 
smaller size; in the small number of somites in apparently complete 
worms; and in having fewer somites with dorsal setae. The shape of the 
brain also is quite different in the two species (PI. II, Fig. 1 and2), as 
shown by a comparison of the following three measurements: median 
antero-posterior axis, greatest lateral diameter, and greatest dorso-ventral 
axis. These ratios for H. forbesi, in the order mentioned, are 4 :4 :3; 
and those for H. emissarius, 5:8 :4. 
The scanty records of the occurrence of H. forbesi give almost no 
information concerning its distribution or the precise kinds of situations 
