[91] NOTES ON ENTOZOA OF MARINE FISHES. 809 



kind of terminal os into which the muscular proboscis can be retracted. 

 The third part is a muscular disc, which bears four auxiliary acetabula 

 on its anterior edge. It is truncate in front, globular in lateral, oblong 

 in marginal view. At its base it forms a collar, with thick, rounded 

 edges, which surrounds the abruptly-narrowed neck. 



Anatomy of posterior segments. — The last three segments were stained 

 with haBinatoxylon and cut into longitudinal sections. The segments 

 are as yet too immature to allow one to say certainly that the genital 

 apertures are marginal. There is, however, a dense, pyriform nuclear 

 cluster towards the front end of each segment and nearer to one mar- 

 gin than the other, which I believe outlines the beginning of the cirrus 

 bulb. There is also a nuclear aggregation at the base of each segment, 

 which probably marks the beginning of the ovary. Although no ex- 

 ternal genital apertures as yet exist, I feel quite confident, from the 

 appearance of these segments, that, when adult specimens of this species 

 are found, the genital apertures will be found to be marginal. 



The sections show first a soft, granular epidermis, which has a tend- 

 ency to slough off. Next a fine granular layer containing delicate cir- 

 cular fibers. Beneath this is a layer with coarse granular and longi- 

 tudinal fibers. The center of the segment is granular with no fibers 

 of any kind. There are, however, mauy clusters of nuclei with a clear 

 space in the center of the cluster. These are apparently sections of tub- 

 ular bodies which are beginning to take shape in the parenchyma of the 

 interior of the segment. Some of these nuclear clusters are elongated. 

 Two rather prominent aquiferous vessels were observed. Each of these 

 lies a distance from the nearest margin equal to nearly one-third the 

 breadth of the segment. These pursued a somewhat sinuous course 

 and passed without interruption from one segment to another. 



The segments are sharply defined, the one from the other. At the 

 dividing line between two segments an abundance of circular or trans- 

 verse fibers is developed. Tue posterior edge of each segment pro- 

 jects a very little to overlap the front end of the succeeding segment. 



Sub family II.— Phyllacanthin^: Van Beneden. 



Calliobothrium Van Beneden. 



The restoration of Van Benedeu's genus Aeanthobothrium necessitates 

 an emendation of the definition of the genus Calliobothrium. The char- 

 acters of this genus, thus emended, following Diesing's definition, are : 



Body articulate taeniseform ; head continuous with the body or separated by a neck, 

 quadrangular, with four angular bothria, which are attached to the head in front by 

 the dorsal face, trilocular ou account of two transverse costae, each armed in front 

 with four simple hooks, and provided in frout of hooks with a versatile supplemental 

 disk, cup-shaped, trilocular or contracted into a globe. Genital aperture marginal. 



