LESUEURIA. 23 



tached to the inner wall, near the upper part of the farrow, separating 

 the lobes from the spherosome. Foster, in 1841, found a species of 

 Filaria, which he called Tetrastoma Playfair'd, upon a species of Cy- 

 dippe y Greene and others have also seen parasites upon Hydroid 

 Medusas ; and finally, in this species, five to eight worms, which re- 

 semble more a leech than anything else, though I cannot refer them 

 to any of the genera which are described, attaining a length of an 

 inch, and even an inch and a half, are frequently found attached to 

 the inner wall, in the upper part of the long furrow, near the eye- 

 speck. Hardly a specimen of this Medusa is found which has not one 

 or two of these parasites. It is a long, flesh-colored, cylindrical worm, 

 with five longitudinal white lines extending the whole length ; the 

 mouth, by which it is fastened to the jelly-fish, occupying the whole 

 of the anterior part. This mouth can be closed, extended to a point, 

 snd, when inserted in the substance of the jelly-fish, it is expanded 

 again like the mouth of a trumpet, and the worm is firmly fastened. 

 These worms are sluggish in their movements, and when detached and 

 disturbed hardly show signs of life by the slow contractions of their 

 body. The worms live several days after they have been separated 

 from the Medusae. 



Naushon, Buzzard's Bay (A. Agassiz). 



LESUEURIA MILNE EDW. 



Lesueuria MILNE EDW. Ann. Sc. Nat., XVI, 1841, p. 199. 



Lesueuria LESS. Zooph. Acal., p. 90. 1843. 



Lesueuria AGASS. ' Cont. Nat. Hist. U. S., III. p. 290. 1860. 



Lesueuria hyboptera A. AGASS. 



In Lesueuria the tentacular ambulacra are by far the most developed ; 

 the locomotive flappers of the short ambulacra extend but to the be- 

 ginning of the auricle ; the immense size of this apparatus, projecting 

 beyond the level of the mouth, and the winding of the tube running 

 through the auricle, before it joins the lateral chymiferous tube, gives 

 this tube a great length when compared to the longitudinal ambulacra, 

 which run in an almost straight course from the abactinal pole till they 

 meet the horizontal part of the tentacular branch which connects near 

 the mouth with the opposite tentacular apparatus. The tentacular ap- 

 paratus is similar to that of Bolina, and is also situated in the short 

 transverse axis. The lobes of a Lesueuria can hardly be called by that 

 name, as what corresponds to the lobes of Bolina are small projections 

 scarcely reaching below the level of the mouth, and in which all we 



