RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 1 73 



tacles varies with the age of the worm, but at maturity there are 

 usually eighteen for each lophophore. They are of moderate length, 

 and of uniform extent, and measure about half a millimeter. Two 

 of them internally, one for each lophophore, are rather longer and 

 larger than the others, and are rendered conspicuous by a large 

 vessel filled with bright green blood. The tentacles are invested 

 with ciliated epithelium, with actively moving cilia, and in all re- 

 spects bear a close resemblance to those of the polyzoa. In the 

 allies of Manayunkia they are regarded as branchial appendages, 

 and usually named cirri ; and although this is unquestionabl}^ cor- 

 rect, as in the case of the corresponding organs of the polyzoa, they 

 perform a varied function, and may, with equal correctness, be 

 called tentacles. 



When Manayunkia is about to withdraw into its tube, the lopho- 

 phores approach, and, together with the tentacles, form a close 

 longitudinal fascicle. Along the lophophores, at the base of the 

 tentacles, there is a row of half a dozen or more brownish pigment 

 spots, resembling eyes, but not having the usual constitution of 

 such organs. The segments of the body of Manayunkia, succeeding 

 the head, are furnished on each side with a fa.scicle of locomotive 

 setae, which is divided into two portions, one usually consisting of 

 shorter setae than the other. The fascicles, when most protruded, 

 project from a papilla, which disappears with the partial retraction 

 of the former. They are projected directly outward or in a slant- 

 ing manner either forward or backward, and are moved in the same 

 manner and by the same arrangement of muscles as in other chaeto- 

 pods. The number of podal setae is from four to ten in each fas- 

 cicle. In several mature individuals the numbers in the different 

 segments were as follows : 8 to 10 setae in the first to the sixth seg- 

 ment ; 6 to 7 in the three succeeding ones, 4 or 5 in the tenth, and 

 3 or 4 in the last segment. 



The setae, Figs. 3, 4, of the anterior segments are longest and 

 range from about 0.15 to 0.25 mm. in length. They consist of a 

 long, straight rod, with a linear-lanceolate blade, tapering into a 

 long filament. The rod varies little in length in the different setse, 

 but the blade varies considerably in this respect. The blade is 

 more or less bent from the rod and is longest in the long setse. 



Except the head and the first setigerous segments, the others are 

 provided on each side with a fascicle of podal hooks, which are 

 situated ventrally behind the bottom of the podal setae. The hooks 

 are 4 or 5 in each fascicle in the setigerous segments from the sec- 

 ond to the eighth inclusive, and are very different from those of the 



