[9] ENTOZOA OF MARINE FISHES OF NEW ENGLAND. 461 
tractile. When the living specimen was viewed from the apex the aper- 
ture (os) could be seen surrounded by many radiating lines like the radiat- 
-ing muscles of theiris. In aside view of amounted specimen a globular 
body about 0.2™™ in diameter can be seen lying in the center of the probos- 
cis and about 0.1™ from the apex. This globular mass has an aperture 
which lies opposite the aperture of the proboscis. It probably repre- 
sents the true apex of the myzorhynchus retracted. The head behind 
the bothria is elongated into a neck-like part, which joins the true neck 
or jointless portion of the body by a definite articulation, which bears a 
faint resemblance to a ball-and-socket joint, in which the anterior part - 
of the neck represents the “ball.” There is also a difference in tissue, 
the neck having, besides longitudinal fibers, transverse fibers and many 
granular cells, while the neck-like portion of the head appears to be 
composed almost entirely of fibrous tissue arranged longitudinally. 
In the other type the pedicels of the bothria are inflated and some- 
what globose; the thickened border of the disk is not so much folded 
asin the first. Thehead behind the bothriais short and turgid. These 
differences, although striking when extreme cases are considered, are 
none of them so profound but that they may be accounted for by sup- 
posing them to represent different degrees of contraction. The bothria 
in the living worm are susceptible of great variety of form. 
The segments begin from 1 to 2™™ back of the head. At first they 
are much broader than long, subsequently they become quadrate, then 
longer than broad. As the segments begin to mature they show a 
tendency to become narrowed anteriorly, with convex margins. <A few 
of the extreme posterior segments are four times as long as broad, ob- 
tuse-pointed in front, posteriorly attenuate, with a truncate termination. 
The genital apertures are marginal, opening a little behind the middle. 
In some they are not exactly on the margin, but may be seen, in a lat- 
eral view, to be situated near the margin and running obliquely toward 
the center of the segment. The penis was retracted in all the specimens 
examined. It could be seen lying coiled up in the angle formed by the 
vagina where the latter turns abruptly from the middle of the segment 
towards the margin. The vagina could be traced from the ovaries in 
the posterior part of the segment along the median line until it reaches 
a point nearly opposite the marginal opening, where it turns abruptly 
towards the margin and opens immediately in front of the penis. The 
vas deferens is represented by aconvoluted mass of tubes in the center 
of the segment. The anterior part of the segment is filled with large 
globular masses (ova). These are surrounded by a thick transparent 
membrane, and have a granular interior. <A layer of oblong granular 
masses, smaller than the interior globular masses, surrounds the latter. 
This layer is adjacent to the marginal wall of the segment and the 
masses are at right angles to it. 
In some specimens the median and posterior segments are very irreg- 
ular in shape. This irregularity is sometimes produced by the appar- 
