23 



bands or fasciculi of striped muscular fibre correspond to the four 

 angles of the peduncle, and are no doubt the agents by which its 

 active movements in all directions are effected. The four gastro- 

 vascular canals run in a straight course from the base of the peduncle 

 to the marginal canal, giving off from their inferior aspect, and at 

 about two-thirds of their length, taken from their entrance into the 

 peduncle, a short, narrower tube, which running down a short way 

 parallel with the main trunk, terminates in the reproductive gland or 

 ovary ; and this short, narrow oviduct, as it may be termed, is lined 

 with very long vibratile cilia, which might readily under some cir- 

 cumstances be mistaken for Spermatozoa. The gastro-vascular 

 canals and the marginal canal are all lined with a glandular epithe- 

 lium, by which term is meant an epithelium composed of cells con- 

 taining a solid granular matter, and which probably are of a glandular 

 or secretory nature. There is an active circulation of fluid in these 

 canals. The marginal tentacles, as has been said, vary considerably 

 in number, and they may usually be observed in all stages of deve- 

 lopment. The perfect tentacle consists of a pyriform bulb which is 

 prolonged into the filiform tentacle. These bulbs are situated on the 

 margin of the disk, from which they project (fig. 3). They contain a 

 cavity which is continuous above with the marginal vessel, and below 

 with the tubular cavity of the tentacle (figs. 6, 7, 8, and 9). The 

 cavity of the bulb is lined with, and in fact its walls as well as those of 

 the marginal canal are constituted of solid glandular cells (figs. 6, 11). 

 These cells, in the cavity of the bulb, I believe to have the property 

 of secreting a luminous material, and indeed to be the principal seat 

 of the luminosity in the present species. A faint blue luminosity 

 may be noticed in these bulbs even by subdued daylight, when the 

 animal is placed in fresh water and quickly examined under the mi- 

 croscope ; and in the dark the phenomenon is very striking. The 

 tentacles have a remarkable power of elongation, and when elongated 

 are thrown into very extraordinary angular curves. At each of these 

 angular bends projects a large filiferous or spiculiferous vesicle. 

 The extremity of the tentacle is slightly dilated, and is thickly beset 

 with similar prehensile vesicles. To this part of the tentacles I have 

 frequently found adherent numerous, globular or elongated cells, 

 containing rounded corpuscles and endued with an active motion. 

 These bodies I looked upon as the sporules of Alga, and as forming 

 probably part of the aliment of the Medusa. 



The formation of the tentacular bulbs appears to commence in a 

 circumscribed dilatation of the marginal vessel, as shown in a, figs. 



