[29] NOTES ON ENTOZOA OF MARINE FISHES. 747 



The head is short, in preserved specimens oblong, or even orbicular 

 in lateral view, sagittate, compressed in marginal view, blunt at apex. 

 Bothria lateral, each with shallow concavity and thickened edges, pos- 

 terior border slightly projecting. Length of bothria in two specimens 

 1.75 mm and 2.4"> mm , breadth 1.58 :um and 2""" respectively. 



That part of the body may be conveniently called the neck, which, 

 along with the head, is inclosed in the cyst-like cavity within the recti- 

 nal walls. It is broader than the head and quite irregular in outline. 

 It is characterized by having the cuticle raised into several irregular, 

 transparent folds. At places the neck is thus rendered much broader 

 than the head. At the point, however, where the rectinal walls are 

 pierced by the neck the latter is compressed on all sides and so reduced 

 to a slender cylinder. At its base the neck enlarges abruptly, becomes 

 transversely striated, and thus merges imperceptibly into the body 

 proper. 



Two alcoholic specimens yield the following dimensions for the head 

 and neck : 



The measurement for the marginal diameter of the head, given 

 above, was made about the middle of the bothria. Of course the mar- 

 ginal diameter taken through the bases of the bothria would approximate 

 that of the neck. The measurements of the neck were made a short 

 distance back of the head and at about the broadest and thickest part 

 of the neck. At the more slender, cylindrical portions of the neck, 

 near the base, the diameter varies from .5 to l mm . 



The body, at first elongated, when placed in sea-water and in alco- 

 hol becomes rather stout. It broadens abruptly back of the neck and 

 soon attains its maximum breadth. In some specimens this is main- 

 tained until near the posterior end, in others the body tapers slowly to- 

 wards the posterior end. The posterior mature segments are very nar- 

 row at their anterior end, with broadly flaring posterior borders. Where 

 a few of these are retained on the strobile, they appear like a nest of 

 cups of graduated sizes, with widely flaring lips, piled one within the 

 other. In cases where the narrow posterior segments have been lost 

 the posterior end of the strobile is often deeply emarginate. The seg- 

 ments begin immediately behind the neck, are extremely regular and 

 very short. Their posterior edges are free and project at right angles 

 to the axis of the strobile. They often become undulate with short, 

 crisp folds, which fact imparts the peculiar characteristic appearance to 

 the worm which doubtless suggested the specific name. 



