stated, the said bucal shield is really situated between the mouth and the anus, I think \vi' 

 may consider it as morphologically answering to the so-called Epistome in the fresh-water 

 Polyzoa. Its enormous development in the i)resent instance seems however to indicate that 

 it must have a very peculiar and important function in the economy of this animal. My ob- 

 servations on the living animal have also guided me to a decided o])inion, to which, however 

 strange it may appear, I have been forced again and again to return, and which I therefore 

 must retain : namely that the animal uses this bucal shield (according to my observations), as 

 a sort of rrcrpi)n/-(ir(ifui. l/i/ mraiis of vhirh it ran drair itself up to the nj)erture of its tube. 

 Since, as above stated, botli Endocyst and all muscles of protrusion are wanting, it is in rea- 

 lity quite inexplicable how the Polyi)ide. which is often found drawn back, not only to the 

 l)ottom of the free cell, but even partially into the corresjionding chamber of the creeping 

 stem, (see fig. 10) should be able in any other manner to get forward again so far as to the 

 aperture of the cell. It might perhaps be supposed that this could be effected by means of 

 the elasticity of the contractile cord: but I have convinced myself that such is not the case, 

 by cutting through the contractile cord at its base; the Tolypide has continued undisturbed 

 its slow protrusion, and has also at length really reached the opening of the cell without any 

 remarkable change. The direct observations made on the uninjured animal have also con- 

 tirmed me in the view expressed above. It will be seen (see fig. 14) that during the slow 

 ])rotrusion of the I'olypide (which often lasts for hours) the Inical shield is always in imme- 

 diate contact with the wall of the tube, the whole of its ventral side being closely pressed 

 up against the same; it retains this position unchanged as long as the protrusion lasts; 

 and the protrusion does not stop until the whole length of the bucal shield is extended out- 

 side of the aperture of the cell: then the I'olypide is completely expanded. On examining 

 more closely this bucal shield (see fig. 4) we observe in the middle of it an ojiaque i)art 

 which seems to contain an interior glandular organ. Contiiuiing the investigation, and slightly 

 pressing the animal, we notice however (fig. 18) that this opaque appearance is not produced 

 by any such internal organ, but by a peculiar and seemingly muscular structure of the sub- 

 stance of the shield itself. It exhibits, seen from below, in the middle numerous small bub- 

 bles situated rather far from each other, or somewhat irregularly formed small cells, which 

 however when more closely examined (and this is particularly evident in those which lie nearer 

 to the periphery of the disc) shew themselves to be the external rounded extremities of small 

 inwardly prolonged cylinders, which together appear to form a thick fascicle of incompletely 

 differenced muscular fibres penetrating into the stalk of the bucal shield. 



The animal is. with the aforesaid exception of the stomach and the intestine, whicli 

 are opaque yellow, colorless and transparent. The tentacular arms, and the tentacles, as also 

 the anterior part of tlie body before the stomach, are covered with numerous very small irre- 

 gularly shaped intensely dark violet spots of coloring matter which also occur on the bucal 

 shield, and expecially on its anterior freely projecting extremity, where they are very close 

 together, forming a large roundish dark spot. In specimens in spirits all these parts are 



■) 



