[83] 



NOTES ON ENTOZOA OF MARINE FISHES. 



801 



particular different from the normal type. The neck, which presents 

 the greatest appareut difference, can hardly be taken, from this isolated 

 example, as a type for a new species. If that part of the head which 

 lies behind the bothria in a normal individual were stretched out, which 

 it may have the power of doing, there would then result a form of neck 

 exactly like that which characterizes this abnormal specimen. 



The absence of segments corresponding to the anterior and median 

 immature segments of the normal individuals constitutes a difference 

 which is much more difficult to reconcile with the typical specific char- 

 acters. If other forms should be discovered auswering to this, which I 

 conceive to be an abnormal form, the discoverer would be justified in 

 erecting a new species. It may be regarded at present as a variety. 



The arrangement of the genital organs in the posterior segment is 

 normal. The segments likewise have a lateral opening for the escape 

 of ova. The size of the ova is the same, viz, .02 to .03 ram in diameter. 

 When placed in alcohol the segments contracted very much in length, 

 while the neck remained relatively unaffected. 



Of the specimens, detailed measurements of which are given below, 

 No. 1 is the abnormal form, No. 2 normal, here repeated for compari- 

 son. The dimensions of the abnormal specimen are those recorded 

 when it was first measured : 



Dimensions. 



Length 



Length of head 



Breadth of head 



Length of neck *. 



Diameter of neck, middle 



Length of first segment 



Breadth of first segment 



Length of last segment 



Breadth of last segment 



No. 1. 



No. 2. 



mm. 



mm. 



14.70 



195. 00 



1.00 



1.45 



2.00 



1.80 



2.00 





.18 





.70 



.50 



1.05 



.70 



1.40 



1.60 



1.23 



1.90 



In No. 2 no dimensions are given for the neck. The dimensions given 

 for the first segment, however, do not differ materially from those of 

 that part of the head which lies behind the bothria. 



In the lot obtained August 13, 1887, among quite normal forms, 

 were some which bore mature segments although much shorter than 

 the normal strobiles. In one of these anomalous forms, measuring 18 mm 

 in length, the head aud first twenty segments were normal in shape aud 

 size and character of the flaps. From the twentieth to the twenty- 

 fifth segment the breadth of the strobile increased rapidly from less 

 than l mm to about 3 mm . There were thirty-six segments in all. The 

 last ten or twelve were about the same breadth, that is, 3 mm , and each 

 was about l mm in length. There were a few other specimens which 

 were much like this one, but longer. They were, in fact, transition 

 forms between it and the normal type. 

 H. Mis, 133 51 



