[147] NOTES ON ENTOZOA OF MARINE FISHES. 865 



,02 mm in diameter at base. When the tentacles are retracted, the head 

 is terminated by a circular opening; the sheath or cavity in which the 

 retracted tentacles lie sometimes extends to, and sometimes beyond, the 

 bothria ; at other times it is wholly in front of the bothria, in which 

 cases the anterior part of the head is prolonged; in one case the length 

 of the head was .34 n,m and the depth of the sheath .18 mm . 



The largest alcoholic specimen yielded the following measurements : 

 Length, C mm ; length of head, .28 mm ; diameter of head, .23 mm ; diameter 

 of first segment, .12 mm ; length of last segment, 1.8 m,n ; breadth, .22 mm . 

 The length of the head in a living specimen was .48 mm , length of stro- 

 bile 4.8 mm . In most of the specimens the first distinct segments begin 

 immediately behind the head. In some, however, there is a slight ob- 

 scuration of the first segments on account of differences of contraction. 

 In the latter cases the first segments have the appearance of a short 

 neck and are broader than in those cases where the first segments are 

 distinct. 



In the measurement of ten alcoholic specimens the maximum length 

 of head was .5 mm , minimum .22 mm , average .314 mm ; maximum breadth 

 .36 mm , minimum .24 mm , average .276 mm . The average length of first seg- 

 ment in these specimens was .038 mm , maximum .04 mm , minimum .()2 mm , 

 while in three of the specimens they were obscure. The average breadth 

 of the first segment was .09 mm , maximum .16 mm , minimum .06 mm . 



Usually the first two or three segments are quite short and crowded 

 together, while these are succeeded by a few rounded segments which 

 impart to that part of the strobile a moniliform appearance. The suc- 

 ceeding segments increase in length rapidly, are distinctly separated 

 from each other, and become detached easily. Very often there is a 

 distinct constriction near the anterior end, with a corresponding swell- 

 ing in the middle. The posterior mature segments are much elongated. 

 In one specimen the last two proglottides, which are filled with ova, are 

 together almost as long as the remainder of the strobile. The shape of 

 the mature segmeuts is quite characteristic. They are elongated, arcu- 

 ate, of nearly uniform breadth throughout, except at a point near the 

 anterior end, where they are narrowed by a neck-like constriction. 

 They are rounded, bluut, and slightly swollen at each extremity. Ova 

 fill the interior completely, with the exception of the cirrus and its 

 bulb, the only part of the genitalia that persists in the mature segments, 

 to within .28 mm of the anterior end, where the uterine cavity stops 

 abruptly, being limited by a transverse partition. The interior of the 

 segment is, indeed, converted into a sac for containing ova. The an- 

 terior end of the mature segment in front of the transverse partition 

 appears to be composed of the muscular walls alone. It probably re- 

 tains some contractile power, and serves as a kind of locomotive organ 

 for the free proglottis. 



The ova consist of globular masses of granules or nuclei, surrounded 

 by a thin transparent envelope, which is sometimes collapsed and irregu- 

 H. Mis. 133 55 



