728 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 



ment, contains the mature ova, and is, furthermore, in the vicinity of 

 the excretory pore, from which the ova evidently make their escape. 



Upon examining a section through one of these mature segments, the 

 ova are discovered to be yellowish, opaque, quite irregular in outline, 

 without hard shells, or rather appearing as if the shells were soft and 

 yielding and had collapsed. While there is much variety in the shape 

 and size of these ova, the prevailing shape is oval and the dimensions 

 about .033 and .018 mm in the two diameters. 



None of the specimens in this lot were, strictly speaking, mature. 

 At least the ova did not appear to be mature, and the folds of the 

 uterus contained, in addition to veritable ova, slightly larger spherical 

 or suboval masses. The latter, in specimens stained with carmine, con- 

 sisted of a clear, pellucid, structureless membrane containing a granu- 

 lar mass, which was frequently deeply stained. There was no tendency 

 whatever for the segments to become detached from each other. 



2. Dibothrium manubriforme Lt. 

 [Report of Commissioner of Fish and Fisheries for 1886, Plate i, Figs. 1-4.] 



In August, 1886, 1 had the opportunity of examining a sail-fish (His- 

 tiophorus gladius) taken off Newport, Ehode Island. I found but a sin- 

 gle intestinal parasite, a Dibothrium, which I recognized at once, in 

 spite of its mutilated condition, to be very near, if not identical with, my 

 2). manubriforme, which was obtained the previous summer from a spear- 

 fish (Tetrapterus albidus). 



The head of the worm could not be found and the entire specimen 

 was in bad condition, owing to the fact that decomposition had set in 

 in the viscera of its host. The specimen was tranferred to alcohol, and 

 the measurements which are given are therefore all from the alcoholic 

 specimen. It is very considerably longer than the specimens obtained 

 from T. albidus, but a careful comparison with those specimens con- 

 vinces me that it is identical with D. manubriforme. 



In order to obtain a more certain identification of this specimen, I 

 made transverse and longitudinal sections of some of the median seg- 

 ments and compared them with corresponding sections made from one 

 of the specimens from T. albidus. This investigation confirmed me in 

 my view that the specimen in question should be referred to D. manu- 

 briforme, and also euabled me to add some additional data to the anat- 

 omy of that species. 



The specimen from H. gladius affords the following measurements : 

 Length, 220 mm ; breadth in front about i mm ; greatest breadth 5 mm , at 

 a point 70 mm from the posterior end ; breadth at posterior end 2 mm , 

 where it terminates in a bluntly rounded point. The body is about 

 1.5 ,nm thick at the thickest point. The worm is therefore rather slender, 

 but this habit might be very much changed by contraction. The dif- 

 ference in leflgth between this specimen and those from T. albidus, the 



