[21] NOTES ON ENTOZOA OF MARINE FISHES. 739 



posterior edge thin and flaring outwards at nearly a right angle. Sooner 

 or later, however, these segments are crossed by transverse rugae, 

 which give rise in turn apparently to secondary and tertiary segments 

 until, in the widest part of the body, the segments or pseudo-segments 

 become so crowded together as to resemble transverse wrinkles. 



The following details with regard to the feature just alluded to, al- 

 though taken from var. a, do not differ materially from what is shown 

 by var. f3. 



About the fifty-second segment, which, in this individual is 20 mm 

 from the head, a median transverse line makes its appearance, which 

 becomes more strongly marked on the next, and on the next yet more 

 pronounced. The fourth primary segment following the fifty-second 

 was plainly divided into two secondary segments, the posterior seg- 

 ment of this pair being the larger. Beyond this point the segments are 

 alternately larger and smaller, until about the seventy-eighth segment 

 where the same phenomenon is repeated, the secondary being divided 

 into incipient tertiary segments, the transverse lines become more dis- 

 tinct, and about the eighty-second segment give rise to distinct tertiary 

 segments. At a distance of 5Q mm from the head the primary segments 

 can still be distinguished by their more prominent projecting posterior 

 edges. The latter are at this point about 1.25 min apart. Between them 

 are six segments which are alternately larger and smaller. The pri- 

 mary segments can be traced for at least 200 mm from the head. Beyond 

 that point no difference could be "discerned, all the segments having 

 become very much crowded and rugoeform. 



In another individual the secondary segments begin about the forty- 

 fifth from the head, and the tertiary about the sixty-fifth. The distinc- 

 tive features of the primary segments are quickly lost. 



In No. 4 of the table the forty-sixth and forty-seventh segments are 

 divided into secondary segments, but no further indication of second- 

 ary segments is visible until the sixty-third. Tertiary segments begin 

 about the eighty-fifth segment, or 65 mm from the head. 



Another specimen, No. 5 of table, is somewhat narrower in habit than 

 the others, and presents more irregularity in the formation of secondary 

 and other segments. The third and fourth segments are welded to- 

 gether. Between the fifth and sixth, sixth and seventh, seventh and 

 eighth segments is a single secondary segment. Each of the next three 

 primaries bears two secondaries. On each of the next two primaries 

 there are three secondaries. On each of the four following primaries 

 there are five secondaries. These may be better described as primary 

 segments of two sizes. There is no indication that the smaller are de- 

 rived from the larger, and these irregularities may be due possibly to 

 differences of contraction. Secondary segments like those observed in 

 the other specimens occur about the ninetieth segment, a distance of 

 some 40 mra from the head. In this individual the greatest breadth is 

 4.5 mm ; breadth at posterior end 1.4 mm ; length of posterior segments 

 about .65 mm . 



