[31] 



ENTOZOA OF MARINE FISHES OF NEW ENGLAND. 



483 



guished as var. y (Plate IV, Figs. 13-1G). These are all immature stro- 

 biles, but are much longer than var. a, and in some cases as long* as 

 var. /?. The strobile is much thicker and rather wider than those of 

 varieties ex and (3. The posterior segments, although not mature in 

 any of the specimens, have a conspicuous male generative organ. The 

 female generative opening is represented by a lateral, median, slightly 

 raised papilliform eminence. Length about 100 mm ; average length 

 of last 30 segments ().6 mm . The posterior segments are 2£ to 3 times as 

 broad as long. 



Measurements made from two mounted specimens. 



Dimensions. 



No. 1. No. 2 



Length of strobile 



Length of bead 



Breadth of head 



Length of neck* 



Breadth of neck in front 



Hreadtli of neck, posterior end . . 



Length of proboscis 



Length of proboscis sheath 



Length of contractile bulb 



Breadth of contractile bull) 



Breadth of strobile back of neck . 



Length of posterior segment 



Breadth of posterior segment 



mm. 



92. 00 

 1.10 

 1.18 

 1. 00 

 0. so 

 0.44 

 0.70 

 0.00 

 0.40 

 0.16 

 0.30 

 0. 50 

 1.60 



mm. 

 82. 00 

 0.70 

 0. 80 

 0.60 

 0.54 

 0.40 

 0.70 

 0.70 

 0. 30 

 0.10 

 0.30 

 0.40 

 1.30 



* In all measurements of the neck the distance from the postero-lateral or postero-marginal edge of 

 the bothria to the posterior edge of the collar is the one given. 



In the second lot containing about fifty specimens, the strobiles are 

 not so mature as those of the first lot. The three varieties noted in the 

 first lot arc not so distinctly marked off. There are, however, two dis- 

 tinct kinds in this lot, which may possibly be due to the effect of the 

 preservatives, but which are sufficiently noteworthy to be mentioned 

 here. In the first the lobes of the bothria are smooth and bounded by 

 regular curved lines as in the first lot, but with the centers of the faces 

 of the lobes slightly hollowed out or depressed, so as to produce the 

 effect of a raised border, and double furrows on the lateral face of the 

 bothriuin. 



In the second the bothria are irregularly furrowed or wrinkled. The 

 bothria are shorter than the neck. The neck is also wrinkled. These 

 differences, although sufficient^ marked to attract attention, do not 

 occasion much perplexity where one remembers the wonderful powers 

 of contractility possessed by the Gestoidea. They might, however, lead 

 to confusion of species in cases where only a few specimens are at hand. 



In describing new species of the Gestoidea, I am satisfied that, where 

 it is possible, a great many specimens should be examined before final 

 conclusions are reached. If this rule had been adopted by former 

 workers in this field of Systematic Zoology the older literature of Hel- 

 minthology would not be in its present state of confusion. 



Attachment to the host. — Those found in the pylorus were not firmly 

 attached, but would release their hold when the point of a scalpel was 



