A CESTODE PARASITE IN THE FLESH OF THE BUTTERHSH. 



By EDWIN LINTON, Ph. D. 



HISTORICAL ACCOUNT. 



During the summer of 1904, at the hil^oratoiy of the Bureau of Fisheries at 

 Woods Hole, Mass., while I was engaged in the study of helminth parasites of fishes, 

 a particular case of parasitism was called to my attention by Dr. Lynd Jones, 

 who had deserved the frec(uency of a parasite in the flesh of butterflsh, Poronotus, 

 triacanthus, which he had been feeding to terns. 



The parasites occur in the muscle tissue of their host in the form of small cysts 

 usually less than 1 millimeter in length. Each cyst consists of a connective-tissue 

 envelop surrounding a plerocercus (blastocyst) in which is the scolex of a cestode 

 worm. In most of the cases examined the scolex was found to be sufficiently devel- 

 oped to admit of its being referred to the species Otohothrium crenacolle. The 

 adult of this species, first found by me in the spu-al valve of the hammerhead shark 

 (Sphyrna zygxna), was made the type of a new genus." 



The genus Otohothrium is distinguished from Rliyncliohothriuin by the presence 

 of two supplemental eversible organs on each of the two bothria. These supple- 

 mental organs are covered with minute spine-like bristles, and appear either as 

 small pits or small papilla^, depending on whether they are inverted or everted. In 

 1901 I recorded from the muscles of the butterfish cestodes that should have been 

 referred to this species, but, their real nature not being recognized at that time, they 

 were wrongly placed in the genus RhyncJiohotJirmmfi For the purpose of comparison 

 with observations recorded for the first time in this paj^er, I make the following 

 extract from the record cited : 



On August 26, 1899, 2 butterfish * * * were submitted to me by Dr. C. Judson Herrick. * * * 

 The muscles between the ribs contained great numbers of small cysts. When one of these was compressed, 

 a blastocyst was liberated, from which, upon further pressure, a larval cestode * * * could be obtained. 

 Forty of these cysts were counted in a space 4 millimeters square. 



Similar conditions were observed in a butterfish brought to me by Mr. E. E. Tyzzer August 17, 1900, 

 and in another examined the following day. 



o Linton, Notes on Entozoa of marine fishes of New England. Report of the Commissioner of Fish and 

 Fisheries for 1887, p. S49-S53, pi. xiii, fig. 9-1.5, and pi. xiv, tig. 1-4. 



b Linton, Parasites of fishes of the Woods Hole region. L'. S. Fish Commission Bulletin for 1899, vol. 

 XIX, p. 453-454, pi. xxiii, fig. 255-256a, and pi. xxiv, fig. 265. 



113 



B. B. F. 1906—8 



