MUSEUM OF COMPARATIVE ZOOLOGY. 139 
gus is lined by a minute chitinous tube, which is intracellular in position, 
and after forming a loop opens out into an intercellular intestine that is 
highly degenerate posteriorly and in the adult lacks a terminal opening. 
The posterior end of the male is a ventrally curved conical intromittent 
organ with a terminal opening. The female is provided with a terminal 
bulb having a central cloacal (?) opening. The small spherical eggs are 
filled with large refractive yolk granules and protected by a shell, the 
thickenings of which become long and pointed spines on coming in con- 
tact with the water. The eggs measure 36-40 „ in diameter without 
the spines, which are 8 to 10 p long. Color of the animal in life gray- 
ish to yellowish white with transparent anterior end. The median lines 
each show two narrow longitudinal bands of dark slate color., 
Length of the male, 50 to 200 mm.; of the female, 30 to 60 mm. 
Diameter, 0.3 to 1 mm. 
Habitat: Narragansett Bay, R. I, A. Agassiz (1870-90), J. W. 
Fewkes (1883); Vineyard Sound, Mass., S. I. Smith (1871), A. E. Verrill 
(1879); Wood's Holl, Mass., W. M. Woodworth (1888), E. A. Andrews 
(1890). 
III. Biology. 
Up to the present time Nectonema has been reported from two places 
only, Newport, R. I., and Wood's Holl, Mass., and the south shore of 
New England may fairly be considered as its home. Here it is not so 
rare as has been supposed, for by systematic search fifteen specimens 
were secured in one summer. The dates of capture of some sixty-five 
specimens show that it may be found from the last of June to the first 
of October, with two maxima, one in July and a second in September, 
more than two thirds however having been caught at the earlier date. 
It is noteworthy that, of the fifteen individuals captured at Newport last 
summer, all were taken while the tide was going out, and on evenings 
when there was no moon, the ordinary time of towing being between 
8 and 10 p.m. The latter circumstance seems to indicate that the 
worms are susceptible to light ; the possible significance of the former 
will be discussed later. It is also an interesting fact, that they were 
caught in towing near the shore, two in fact having been dipped up one 
evening in July when filling a pail with water at the landing of the 
1 I do not believe that towing has been done in this region with any regularity 
at other times of the year, so tbat these dates cannot be accepted as fixing *he 
time of its occurrence. 
