LOPHOPUS CRYSTALLINUS. 85 



Full-grown specimens have the endocyst deeply lohed, so as to cause it to present a 

 kind of palmate appearance. The intervals of the lobes, however, are nearly filled by the 

 gelatinoid ectocyst. Young specimens are not lobed, and then they correspond to the "Bell- 

 flower Animal " of Baker. 



Both Baker and Van Beneden ascribe to this animal a power of locomotion. To the 

 existence of this power, however, my own observations are opposed ; the colony is certainly 

 very easily detached, and will when all is quiet again readily fix itself, so that a passive change 

 of place may in this way be effected ; but though I have had numerous specimens constantly 

 under my eyes, I have never witnessed anything like the active locomotion of Cristatella. 



The ectocyst is perfectly colourless and transparent, the endocyst and polypides are pale 

 brownish -yellow. 



The statoblasts are larger than those of any other fi-esh-water Polyzoon, except Cris- 

 tatella. They are of an elliptical form, with the long diameter prolonged at each extremity 

 into a short acute point. 



L. aysTallinus is one of the largest of the Polyzoa, and this circumstance, together with 

 the transparency of the ccencecium, renders it peculiarly well adapted for examining the 

 structure of the class. 



In many cases the perigastric space in LojjJtopus was found to contain numerous spherical 

 bodies (PI. II, figs. 16 — 23), which floated freely in the perigastric fluid, where they were 

 rapidly whirled about under the influence of the currents. They varied much in size, some 

 being about the tj'ojj of an inch in diameter, while others were as large as an ordinary Folvox 

 glohator. Some were seen to consist in a spherical transparent cell, with nearly colourless 

 granular contents, involving numerous minute spherical bodies, apparently young cells ; these 

 contents were aggregated on the inner surface of the wall, where they constituted a thick, 

 somewhat irregular layer. In other cases the contents were seen to be entirely resolved into a 

 brood of young cells, which completely filled the parent-cell ; while in the largest individuals 

 these secondary cells might themselves be seen in various stages of growth and subdivision, 

 some presenting the appearance of a little spherical granular mass with visible nucleus, but 

 without distinct cell-wall, others somewhat larger, with the cell-wall become distinct, and 

 others in which the granular contents had retired from the cell-wall towards the centre of the 

 cell, where they were to be seen surrounded by a colourless fluid. In a still further stage the 

 contents had become divided into two masses, while in still more advanced cases each of these 

 masses might be seen again dividing into two others, the subdivision being preceded by the 

 appearance of two nuclei in each mass. The whole of this brood of young cells was ultimately 

 liberated by the rupture of the large parent-cell, and then floated away in the perigastric fluid. 

 That the bodies now described had no necessary connection with the Polyzoon in whose 

 interior they occurred, must, I think, be admitted ; their presence is, without doubt, purely 

 parasitical. 



