27 



usually, however, there is one on each side of the larger tentacles, 

 but only on one side of the smaller. They are round, one -fortieth 

 of a line in diameter ; consist of a tolerably thick membrane, and 

 contain one to nine and even more round corpuscles. If there is 

 only one corpuscle, it is lodged exactly in the middle of the vesicle ; 

 but when more are present, they are placed either in two groups, to- 

 gether, or arranged in a single row at the border of the vesicle 

 (beisammen oder eigeln ane inauder gereiht). Their size varies from 

 the one-three-hundredth to the one-hundred-and-fiftieth of an inch. 

 I have never observed motion in them. Muriatic acid dissolves 

 them and causes the vesicle to collapse. At the point where the 

 latter is placed upon the marginal vessel there is a slight depres- 

 sion ; this is filled' up by a yellowish-green substance, in which the 

 vesicle itself is imbedded to the extent of one-third of its circum- 

 ference. This structure I look upon as a ganglion, although histo- 

 logically this cannot be demonstrated." 



In Geryonia planata, the structure of these bodies would appear to 

 be the same as in the above. 



In Thaumantias leucostyla (Will), also a naked-eyed species, " The 

 auditory capsules are stated to be situated below the basis of the 

 marginal tentacles on a minute projection. They are about one- 

 sixtieth of an inch in diameter, and contain a corpuscle one-two-hun- 

 dredth of an inch in size. They do not occur under all the ten- 

 tacles." 



In Ephyra, a covered-eyed species, the marginal vesicles are placed 

 in the angle between the two terminal lobes of each segment, upon 

 a thick peduncle ; they are completely filled with about thirty rhom- 

 boidal crystals, the largest of which are the one-hundred-and-fiftieth 

 of an inch in length, and the two-hundredth in width. The vesicle 

 itself has a diameter of one -fiftieth of an inch, and only two -thirds 

 of its circumference are free. The other third is imbedded in a 

 round or elongated cellular substance very distinct from the substance 

 of the body, by its less pellucidness and a yellow colour. The pe- 

 duncle is the continuation of an elevated sharp ridge, running from 

 the mouth to the middle of each lobe on the under surface, and is 

 continued somewhat outwards on the latter itself, where it is gradu- 

 ally lost. But at the point where the middle third of this ridge forms 

 the peduncle of the auditory capsule, it appears as if this peduncle 

 had four angles, two more prominent on the inner side, and two less 

 distinct on the outer. 



What is said respecting these marginal bodies, in the beautiful 



