1910.] J. STEPHENSON: On some Aquatic Oligochaete Worms. 239 
setae of a specimen of N. communis, var. punjabensis, from Shali- 
mar, near Lahore. 
Ventral setae of segments ii—v :—length 94 », shaft not much 
curved, thinner than those of the more posterior segments. Distal 
prong half as long again as proximal, the latter being twice as 
thick at its base. Nodulus equal on both sides of shaft, slightly 
proximal (12 : 13). Four setae per bundle. (Fig. 4a.) 
In segments vi and onwards :—length 84-87 y», shaft stouter 
and more curved than in anterior segments ; distal prong 1} times 
as long as proximal, which latter is double as thick at base; 
nodulus equal on both sides of shaft or slightly more marked on 
the side of the distal prong; distal to middle (4 : 5, or, in a more 
posterior segment, Ir : 16). Commonly four setae per bundle, 
sometimes five, or three. (Fig. 40.) 
Dorsal setae in bundles of one hair- and one needle-seta ; the 
latter 69 » long, the shaft slightly curved beyond the nodulus 
in the form of a sickle, and very slightly in the reverse direction 
proximal to the nodulus; finely bifurcated at the extremity ; 
nodulus distal (3 : 8). (Fig. 4c.) 
I may perhaps be permitted to add a few words in regard to 
this form, with reference to Piguet’s criticisms in his recent paper 
(Rev. Suisse de Zool., Tome 17, Fasc. 1, 1909). An examination 
of the reproductive organs has, as already mentioned, resulted in 
approximating this form to N. communis rather than to N. vari- 
abilis, to which latter, however, the setae of the Punjab variety 
show the greater resemblance. A renewed examination of the 
“thorn-like projections’ of the dorsal setae, and the facts that 
such projections may be present on the ventral setae also (though 
rarely), and that (in a Pristina, for example) they may cluster 
round the dorsal setae in such lengths and numbers as to give the 
seta the appearance of a miniature ostrich feather, has convinced 
me that Piguet is right in supposing them to be a cryptogamic 
growth. 
With regard to Piguet’s suspicion that there may have been 
more than one species or variety of Nats among the specimens 
which I used for my description,—and that my account of the 
variations in the dorsal setae may be due to this cause, I will not 
at present venture an opinion, since I have not yet had time for a 
renewed investigation. But I do not expect to be able to record 
any very large number of aquatic Oligochaeta from the environs 
of Lahore. With the exception of artificial tanks in pleasure 
gardens or in connection with manufactories, and the canal, the 
only body of water is the river Ravi. The artificial tanks, much 
to the detriment of zoological studies, undergo periodical cleansing , 
—I think much more frequently nowadays than some years ago; 
and the irrigation canai runs for a few days, and is then dry for a 
longer or shorter period,—hence it is useless in this connection. 
There are no natural freshwater ponds or pools except in the 
rains ; and the months from October to June inclusive are (with 
