202 BULLETIN OF THE 
The anterior end (Figs. 5, 6, 7, 8) is blunter than the posterior (Fig. 10), 
and in one specimen has a clear cavity within, easily seen through the cephalic 
walls, in which, as Verrill has already mentioned, four transparent, nucleated, 
cells lie. The month cannot be observed very distinctly, but is discovered by 
close observation on the ventral side of the head as a narrow longitudinal * slit. 
There are no cephalic tentacles or other appendages to the head. A pigment 
spot was noticed in the walls of the head just in advance of the transparent 
region, but whether it is an ocellus or not was not determined. The digestive 
tract, which is of varying diameter, but always small as compared with that of 
the body cavity, extends from one extremity of the crown to the other. The 
walls are muscular, and at times have a rhythmic pulsatile motion, which may 
be seen through the body walls, The anus is terminal, and mounted on a 
curved caudal prolongation of the body, slightly enlarged at its extremity. 
According to Prof. Verrill the posterior end of the male and female Nectonema 
differ from each other, and he speaks of a peculiar “ papilla” found in this 
region of the female. 
The stomach and intestine often become so inflated that they fill the body, 
so that they cannot be distinguished from those of the body cavity. The 
“yellowish white organ [ovary ?] extending from near the head to the tail,” 
mentioned by Prof. Verrill, was observed in one specimen. 
The affinities of this singular worm with known genera are somewhat doubt- 
ful. Prof. Verrill, with an implied expression of doubt, refers it to the Nema- 
todes. That reference seems to me a proper one, but from what little is known 
of its anatomy it can find few near relatives among the genera now known in 
this group of worms. It must, if a Nematode, take its place near the Chetoso- 
mide, or perhaps by the side of that strange worm Hubostrichus, of even more 
problematical affinities, described by Greef,t from the North Sea. If near the 
latter, it isas a giant with a pygmy, for Eubostrichus is but 8 mm. in length, while 
Jectonema is ten times as large. The matted covering, formed of hairs, which 
characterizes Eubostrichus according to Greef, does not exist in Nectonema. 
There is, however, a tendency for something like this covering to form on the 
hairs along the lateral lines. Nectonema is a genus with close affinities on the 
one side with the Nematodes, while on the other it presents strongly marked 
Cheetopod characters. The segmentation so pronounced on the lateral bands, 
and the double row of hairs upon the sides, point to the Annelides as its near- 
est allies. The connecting web of the lateral hairs recalls the lateral fins of 
Sagitta. 
* In Prof. Verrill’s specimen, “a transverse whitish band seemed to indicate the 
position of the mouth.” 
¢ Arch. f. Naturg., 1869. 
CaMBRIDGE, December, 1883. 
