750 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [32] 



that part of the body which becomes enveloped by the tissues of its host 

 degenerates into a fleshy cylinder from which all traces of segments 

 are lost. It is easy to see how this result can follow upon such condi- 

 tions when it is remembered that about the only indication of a seg- 

 mented condition is the thin projecting posterior edges of the segments, 

 so that when these disappear the central core of the body would appear 

 without segments. For convenience of description, however, it will be 

 well to call that part of the body the neck which in the adult becomes 

 so distinctly modified at the point of attachment. 



Olsson states, with a query, that the genital apertures are lateral. 

 Since the apertures in question occur about the middle of the free 

 marginal edges of the segments, and the cirrus pouch lies wholly 

 within that free margin, I think there should be no hesitation in say- 

 ing that the genital apertures are marginal. 



Habitat. Xiphias gladius. Off Martha's Vineyard, Massachusetts, 

 July 25, 1887. In rectum, five adult specimens, one young. 



6. Dibothrium rugosum Eudolphi. 



[Plate in, Figs. 7-10.] 



Boihrioceplialus rugosus, Riulolplii. Eutoz. Hist., in, 42 ; Sytiops., 137. Leuck- 



art, Zool. Bruchst.. 57. Dtijardin, Hist. Nat. cles Helm., 617. Cobbokl, 



Traus. Liiin. Soc., xxir, 158, 159. Olssou, Lund's Uuiv. Arsskrift, iv, 10, 



PI. in, Fig. 65. Von Linstow, Compend. Helm. 236. 



Dibothrium rugosum, Rudolph!, Diesiug, Syst. Helm., I, 591; Revis. Ceph. 



Par., 240-241. G. R. Wagener, Natuurk. Verb. Haarlem, xiu, 93. 

 For older synonymy see Diesiug's Syst. Helm. 



Head sub-sagittate, witb oblong lateral botbria. Body with a median furrow and 

 unequally articulate. Lengtb, 300 to 900 mm . Dicsing. 

 Lengtb, 300 mm to l m ; breadtb, 1.2 to 4 mm .Dujardin. 

 Genital apertures marginal, irregularly alternate. Olsson. 



I have referred to this species a small lot of Dibothria from the intes- 

 tine of the cod (Gadus morrhna). The specimens were collected by 

 Mr. Thomas Lee, of the U. S. Fish Commission steamer Albatross, on 

 the Grand Banks. Mr. Lee stated that he examined one hundred and 

 fifty cod and found parasites in but a few of them. 



Each of the specimens in this lot has the head and anterior part of 

 the body buried in the pyloric creca, where they have undergone degen- 

 eration to such an extent that no appearance of bothria remains. 

 Around the parts thus enveloped by the creca is a yellowish waxy de- 

 posit, the degenerated tissue of the caeca. This adventitious tissue in- 

 vests the worm, so closely that it would be absolutely impossible for the 

 parasite to free itself from its host. This feature is mentioned also by 

 Cobbold, who makes the following statement with regard to Dibothria 

 from the cod : 



In a cod examined on the 15th of March, 1855, two specimens of Hothriocephalus 

 rugosus had severally attained a length of 15 inches, and their anterior segments, for 

 an inch or more downwards, were so liruily impacted within the pancreatic caica 



