200 DK. T. S. COBBOLD ON DISTOMA CLAVATUM 



Remarks on Distoma clavatum from a Sword-fish. By T. Spencer 

 CoBBOLD, M.D., F.E.S., E.L.S., Lecturer on Comparative 



Anatomy at the Middlesex Hospital. 



[Eead Jan. 17, 1867.] 



Dtjeing my stay at Lynn, Norfolk, in August 1865, a fine ex- 

 ample of the common Sword-fish {Xiphias gladius) was cast 

 ashore in the estuary. Although quite dead when discovered, 

 the creature was in a tolerably fresh condition ; and when sub- 

 sequently dissected by Dr. John Lowe and myself, some of its 

 internal parasites were still alive. Respecting the structure of 

 the fish I do not propose to ofler any particulars ; but it may be 

 worth while remarking that it measured exactly ten feet and two 

 inches from the tip of the snout to the end of the upper division 

 of the tail. Several other careful measurements were taken, which, 

 together with useful data regarding the natural history of the 

 species, will, I believe, be placed on record by Dr. Lowe, who has 

 for some years past devoted much attention to the zoology of the 

 Norfolk estuary, and especially to the fishes. 



Five diff"erent species of Entozoa were encountered in the flesh 

 and intestinal canal of this Sword-fish- — -an,\iie\j , Distoma clavatum, 

 Ascaris inciirva, Botliriocevlialus plicatus, Tetrarliynclius attenu- 

 atus, and a form of Scolex referable to a second species of the 

 last-named genus. On the first-named of these parasites I pro- 

 ceed to offer some observations — not, indeed, with the view of 

 seeking to establish the existence of new species by splitting up 

 an old one, but rather for the purpose of showing that the 

 Distoma clavatum may be viewed as representing a variety of 

 forms hitherto regarded as separate species hy helminthological' 

 ■^Titers. 



Distoma clavatum. — Five examples of a trematode, which I 

 believe to be referable to this species, were found in the stomach. 

 They severally varied iu length from four lines to two inches. 

 They were dead, and apparently only very slightly if at all de- 

 composed. They diflered somewhat in shape; but all had the so- 

 called head and neck directed backwards. In one example the 

 anterior slender moiety formed a right angle with the body 

 proper, the margin, of the ventral acetabulum, viewed from 

 before, being, as it were, placed on a level with the oral sucker. 

 Below the ventral sucker, the two largest specimens were dis- 

 tended with eggs and black pigmentary matter, all of them 

 showing, internally, a dark spot near the centre of the neck. All 



