[107] NOTES ON ENTOZOA. OF MARINE FISHES. 825 



27. Rhynchobothrium bulbifer Lt. 

 [Plate x, Figs. 8 and 9, and Plate xi, Figs. 1 and 2.] 



Rhynchobothrium tenuicolle End., Lt., Report of U. S. Fish Commissioner 



for 1886, pp. 486-488, Plate v, Figs. 17 and 18. 



Since publishing my first notice of this parasite, I have encountered 

 it on several different occasions in the same host in which I first found 

 it, viz, the smooth dog-fish (Mustelus canis). A careful revision of the 

 subject in the light afforded by this additional material has convinced 

 me that I was mistaken in referring this species to R. tenuicolle. I have, 

 indeed, found it necessary to make a new specific name to accommo- 

 date it. 



The species R. bulbifer may be briefly described as follows : Bothria 

 two, suborbicular, but somewhat variable, with a raised and rather 

 thick border, emarginate on posterior edge, more or less approximate 

 in front, divergent posteriorly. The head in marginal view is there- 

 fore sagittate. Neck long, slender, subcylindrical, tapering gently 

 for a short distance back of the head, then increasing in diameter 

 slightly to the contractile bulbs. Immediately behind the bulbs there 

 is a constriction, distinct in some, slight in others, behind which the 

 neck enlarges to form a rounded or even globular base which is sep- 

 arated from the body by a profound constriction. The body behind this 

 constriction is slender, subcylindrical, and for some distance is without 

 segments or transverse markings of any kind. The first segments are 

 rather faintly outlined ; they are squarish, or even a little longer than 

 broad ; the segments increase in length towards the posterior end ; the 

 posterior segments are very large, three to four times as long as broad, 

 rounded at the two extremities, held together feebly by narrow commis- 

 sures, separating easily from the strobile. Free proglottides very active 

 and apparently continue to grow after their release from the strobile. 

 Proboscides very long, slender, and graceful, armed with hooks of dif- 

 ferent shapes. Proboscis sheaths slender, spiral ; bulbs linear, oblong. 

 Genital apertures marginal, usually indicated by a broad, square notch 

 about the posterior third of the segment. Entire strobile lanceolate, 

 with finely serrate margins and few, rarely as many as twelve, segmeuts. 



Length, 20 to 40 mm ; length of free proglottides as much as 12 mm . 



Habitat. — Mustelus canis, spiral valve, of frequent occurrence, July and 

 August, Wood's Holl, Massachusetts. 



