MUSEUM OF COMPAKATIVE ZOOLOGY. 167 



the dip-net, in the month of May. I have given a figure, Plate VII. fig. 9, of an 

 octant of this immature Cyanea seen from the oral side. This octant, as the 

 other seven wliich compose the disk, bears an otocyst, and hence I shall in my 

 description designate it as the sense octant. The lappets, one on each side of 

 the radius in which the otocyst lies, are called in my description the sense lap- 

 pets, or lappets of the sense organs. 



The movements of the umbrella of the ephyra are very rapid, and when at 

 rest its lobes are thrown backward and upward, as in Plate VII. fig. 4% expand- 

 ing the oral folds and causing them to project in the manner shown in that 

 figure. The diameter is between an eighth and a quarter of an inch. It has a 

 light bro%vn color, and at a superficial glance resembles an ephyra of Aurelia. 

 The likeness of the ephyra of Cyanea to that of Pelagia cyanella as figured by 

 Prof. Agassiz, or of CJirysaora as represented by Glaus, is so close, that it might 

 easily be mistaken for that of either of these genera. 



There are eight sense lobes in the ephyra, as in the adult Cyanea. The in- 

 cisions in the margin separating the lobes are very deep, and so wide that these 

 bodies are removed from each other by an interval equal to the width of the 

 lobe itself. The whole aboral surface of the disk is covered with very minute 

 papillae, which a little later in the growth of the ephyra elongate into promi- 

 nent filaments, of which I shall speak later. To anticipate, let me say that 

 the developed filaments are figured in Plate VII. fig. 1. The whole disk of the 

 ephyra, especially the margin of the disk, has very thin walls. 



The structure of the " lower floor " of the umbrella in the ephyra is very 

 complicated. In the centre of the disk on this side there is found a mouth, 

 which is a simple opening surrounded by a slightly raised, quadrate-shaped 

 ridge, forming the lips. The elevation of this ridge above the lower floor of 

 the ephyra is very slight, and the lips are as yet without folds. There are, 

 however, four re-entering angles, one on each side of the rectangular ridge, 

 which impart to the mouth as seen from below a cross-shaped outline. Plate 

 VII. figs. 9, 10. The points of this cruciform figure later elongate, and, hang- 

 ing down Hke curtains, form the complicated folds of the oral appendages to the 

 mouth. 



From the under surface of the "lower floor" of the ephyra in the interval 

 left by the re-entering angles in the ridge about the mouth there is formed a 

 tentacle (S), difi'ering in no respect from the first tentacles foimd on the 

 umbrella margin. As there are four of these re-entering angles about the 

 mouth, there are at first only four of these tentacles, one for each angle. Each 

 one originates as a simple bud, and as they become more developed smaller 

 buds form near and upon the base of that first developed. Plate VII. fig. 9*. 

 The position in which this tentacle is found refers it to the sexual organs. In 

 the adult Cyanea these tentacles are very numerous, and are found in rows 

 above the sexual glands. In my figure, Plate VII. fig. 13, the natural position 

 has been reversed, and the row of sexual filaments is found below the ovaries. 

 In the genus Cyanea the sexual filaments of the adult are very minute ; in 

 Polybostricha dubia, Br. they reach a much gieater development. 



