402 !'lf()V]JL'DL\<iS or 'I' HE XATIOXAL MUSEUM. voi.. m. 



radial, two adradials, and one or two siibradials in each quadrant. 

 And their respective lengths, the former longest, the latter shortest, 

 show that they are developed in that relative order. The interra- 

 dials reach hardly haK way from margin to apex (fig. 1), i. e., are rela- 

 tively shorter than in Olindias or Olindioides; but perhaps they had 

 not reached their final development. 



The gonads occupy most of the length of the radial canals, leaving 

 only short proximal and distal portions bare (fig. 4). In the one 

 specimen they are simple, narrow folds hanging vertical from the oral 

 sides of the canals, folded in a slightly wavy fashion, i. e., much as in 

 half grown Gonionemus murbachii and G. vertens, without any trace 

 of the papilhform processes so characteristic of Olindias. 



The structure and location of the marginal organs, i. e., tentacles 

 and otocysts, is as follows. As pointed out above, the tentacles are 

 all of one kind, corresponding both in structure and in location to the 

 primary tentacles of Olindias; and not only are there no velar tenta- 

 cles; but even the marginal tentacular bulbs, so characteristic of 

 Gonionemus, are likewise lacking. The total number of tentacles is 

 107, i. e., 28, 22, 24, and 29 in each quadrant, besides the four radials, 

 of various sizes, and evidently of various ages. The four radials are 

 largest; next in size are the four interradials, situated opposite the 

 four interradial centripetal canals; next the eight adradials, corre- 

 sponding to the eight adradial canals. In each quadrant there are 

 one or two other large tentacles (opposite the subradial canals) ; and 

 a considerable number of small ones, showing every stage in devel- 

 opment from mere knobs to fully formed organs. Evidently the order 

 of development for tentacles, as for canals, is radial, interradial, 

 adradial, followed by subradials in irregular succession. The very 

 youngest tentacles stand freely on the bell margin, pointing down- 

 ward. But as they grow older (as illustrated by tentacles of succes- 

 sive sizes) they turn upward against the beU (fig. 2), and come to lie 

 in grooves in the exumbrella. In the case of the largest tentacles 

 these grooves are very deep (fig. 3), but they are all open, the jelly 

 never closing over the root of the tentacle; and the oldest tentacles 

 are so large that probably this is the final state. 



There is a thick, opaque kidney-shaped nematocyst pad (fig. 2) 

 associated with each large tentacle, lining the distal end of the groove 

 in which it lies; itself forming a groove roughly triangular in cross 

 section, and continuous both with the exumbrella and with the 

 ectoderm of the oral face of the base of the tentacle (fig. 3) . These 

 pads vary in size with the size and age of the tentacles to which they 

 belong, and are foreshadowed in the very youngest, which project 

 free from the margin, by a thickening of the ectoderm at the base 

 (fig. 2). The oldest tentacles emerge from the surface of the bell at 

 about one-fifth the distance from the margin to apex; the younger 



