254 Dr. R. von Lendenteld on Guard-Polyps 
which are placed in front of the nutritive animals. Further, 
they may sometimes occur in the genus Antennularia. In 
other Plumularide, which, on account of their peculiar gono- 
phores, will necessitate the establishment of a new genus, I 
have observed such machopolyps together with guard-animals 
bearing urticating capsules. ‘They do not differ essentially in 
their structure from those above described. The greatest 
difference is that ¢nstead of urticating capsules they possess 
adhesive granules which are exactly similarly formed to the 
corresponding elements in the tentacles of the Ctenophora. 
The adhesive animals, as I will briefly designate these 
machopolyps, are distinguished by their extraordinary mobi- 
lity. If an occasional change of form is possible to the 
urticating guard-animals, the adhesive animals can entirely 
draw themselves out into long fine threads, at the extremity 
of which there is then a bulbous dilatation, which on its part 
is capable of considerable change of form. 
In these guard-animals we can detect surface-cells, sub- 
epithelial muscles and ganglia, the supporting lamella, and 
endodermal axis. ‘The thickened terminal part consists of 
pyramidal cells radially arranged, all, or the greater part of 
which, produce adhesive granules. Thus we find in each of 
them a rounded drop of asirongly refractive substance ; and by 
this means these cells acquire exactly the appearance of gland- 
cells. The drop originates at the narrowed centripetal end as 
a small vacuole, and migrates during its growth towards the 
widened centrifugal end of the cell. The perfect adhesive 
granule attains nearly the diameter of the free surface of its 
formative cell and is globular; it projects pretty far above 
the surface of the terminal enlargement of the guard-animal. 
Such mature adhesive granules generally occur in considerable 
number; but they do not stand so close together as on the 
surface of the prehensile apparatus of the Ctenophora, and 
never show that regular arrangement which Chun figures* in 
Euplocamis  stationis. The great similarity between our 
guard-polyps and the prehensile filaments of the Ctenophora 
strikes one at once. ‘I'he difference consists essentially onl 
in the fact that the filaments themselves in the Plumularide 
are not spirally rolled up. We shall revert further on to the 
analogy of these weapons. Allman f figures an Antennularéa 
the guard-animals of which are branched. In those Australian 
species of that genus which contain only machopolyps with 
adhesive cells, 1 have only met with ramifications when cer- 
* ‘Die Ctenophoren des Golfes von Neapel,’ pl. xviii. fig. 11. 
+ ‘A Monograph of the Gymnoblastic Hydroids, vol. i. p. 116, 
