[5] ENTOZOA OF MARINE FISHES OF NEW ENGLAND. 457 



bead, is still noticeable on tbe median segments and also on tbe poste- 

 rior ones, but is not so plainly marked on tbe latter as on tbe two former. 

 In one specimen examined tbe first six segments did not sbow tbis alter- 

 nation in size. In tbe next fourteen segments, bowever, tbe alternation 

 was quite evident. Tbe small anterior segments are terete, subtrian- 

 gular in outline, narrow in front, wide bebind, tbe length nearly equal 

 to tbe greatest breadtb. Tbe succeeding segments are nmcb broader 

 tban long. At tbe widest part tbe ratio of the breadtb to tbe lengtb 

 is as much as fourteen to one. As the segments increase in width they 

 become much crowded together and thickened. In one specimen, meas- 

 uring 140 lum , the segments increased in width uniformly for about 100 mm 

 from the head; from that point they remained about tbe same size until 

 near the posterior end, where they began to be elongated and at the 

 same time became narrower and much thinner. The crowding together 

 of the median segments is not due to contraction, but seems to be a per- 

 manent characteristic of the species. In some very young specimens 

 the same character was observed. The general form of these worms, 

 both young and adult, was persistent. Although kept for some time 

 in water they were not observed to change their form in any essential 

 particular from that given in the sketches. 



In alcoholic specimens a dark median line will be noticed extending 

 from tbe posterior end to the middle or anterior third of the strobile. 

 Tbis is due to tbe centrally situated ovaries, which are crowded with 

 eggs. The genital apertures are lateral and may be traced in an irreg- 

 ular zigzag line on one side from about the anterior third of the body. 

 In the mature segments they are rendered obscure, if not wholly oblit- 

 erated, by tbe mass of eggs with which the center of the segment is 

 filled. Tbe eggs are white, opaque, oval ; lengtb, .045 !mn ; breadtb, 

 .03 mm . Associated with these perfect eggs are masses of others which 

 become transparent when treated with oil of cloves or other strongly 

 refracting media. These seem to be imperfect eggs which have not be- 

 come invested with the thick hard shell which covers the perfect eggs. 



An adult specimen gives the following measurements : 



Millimeters. 



Length of strobile 133. 00 



Length of first series of segments 17. 00 



Length of head 3. 50 



Breadth of head in front, widest part 1. 00 



Average length of segments in first series 0. T>0 



Breadth of widest segments, median 6. 50 



Length of widest segments, median 0. 25 



Length of posterior, mature segments 1. 00 



Breadth of posterior, mature segments 2. 50 



In another specimen tbe bead and first segments give tbe following 

 measurements : 



Millimeters 



Length of strobile 140. 00 



Length of head and first series of segments 30. 00 



Length of head 3. 00 



