7 
but the filiform part of the tail being rather long it still more 
recalls that of H. longicauda Ditl.; from this species it does how- 
ever differ in the feature, that the filiform part of the tail is bent 
inwards and forms a hook (fig. 4, PI. I). 
As in other species of this genus the cuticle is striated and in 
its deeper layer set with minute points. In the front end of the ani- 
mal these points are larger and more prominent than in the other 
parts of the body; they are arranged in transverse rows, a feature 
which holds good in the greater part of the body; only in the 
hind-part the arrangement of the points is more irregular and the 
single rows more indistinct. Along the lateral fields the punctation 
is relatively coarse and grows finer dorsally and ventrally. 
No bristles have been observed on the head; a ring of exceed- 
ingly tiny and delicate papillæ seems to replace them, but the 
number and arrangement of these latter I have not been able to 
ascertain. The lateral organ is spiral-shaped, as usual in this genus; 
in the species under consideration it forms a rather dense spiral, con- 
sisting of about six loops which are cephalo-caudad compressed, 
so that the long axis of the spiral is situated vertically on the 
longitudinal axis of the body. 
The buccal cavity is of the well-known shape usual in this 
genus. It is divided in two parts, the foremost of which is more 
spacious and nearly funnel-shaped; it grows successively narrower 
towards the posterior part which is of about equal width until its 
base. The chitinous rods supporting it are rather thick and strongly 
chitinized. The oesophagus is of about equal width throughout its 
whole length. The nerve ring is indistinct but, as far as I have 
been able to ascertain, it is situated somewhat in front of the 
middle of the oesophagus. Regarding the roaming habit of the Hali- 
choanolaimi it is of some interest that the entire digestive tube 
is coated with a deep brown pigment layer. The intestine is more 
strongly pigmented than the oesophagus, especially the antevaginal 
part of the intestine. As to the oesophagus this feature is seen 
plainly in fig. 3, PI. II. 
Excretorial pore was not observed, nor ventral giand; but in 
all probability this organ does not lack as it is present in related 
forms. The vulva is found somewhat in front of the middle of the 
