130 ZOOPHYTES. 



afforded by the Plumatella, on this interesting department of the arrange- 

 ments guiding the universe. 



The organic parts, by which our remarks must be confined to the 

 hydra, are not dissimilar in the tribe of lunate fresh-water zoophytes. I 

 speak only of general appearances, for perhaps, considerable distinctions 

 exist in reality. 



The inorganic parts of the Plumatella, however, are very different 

 from those of the two preceding genera, the Cristatella and the Alcyo- 

 nella. I would not be understood to affirm, however, that the sole of the 

 former, or the subordinate stratum of the latter, is absolutely of that de- 

 scription. But all the skeleton of the Plumatella is tubular, nor does this 

 tubular portion decay with the animated portion. 



The present zoophyte propagates by ova like the others. It is diffi- 

 cult to say where they are generated, for here there is no substantial mass 

 amidst which their elements may be reposited, as in the Cristatella and 

 Alcyonella. They are most conspicuous when occupying the tubular parts 

 of the Plumatella. 



The specimen, Plate XXXII. fig. 8, recently quoted as occupying 

 the leaf of a yellow Iris, was removed from its native site on the 21st of 

 September, while the hydrse were in great vigour. Numerous ova occu- 

 pied the tubular parts, but in the hydrse none were observed. Many lay 

 below them in the hollow ramifications. There they were arranged in 

 lines or curves according to the form of the parts, which are no wider 

 than the diameter of the ovum. Twenty or thirty were in contact, their 

 position nearly horizontal. — Fig. 10. 



This ovum much resembled that of the Alcyonella stagnorum, though 

 larger. It was of lenticular form, the disc or centre yellow with a dark 

 circumferential ring and a smooth edge, fig. 11. It appears to me that 

 the ovum of the Plumatella is originally white. As the leaf of the Iris 

 decayed, the parts of the skeleton of the specimen became admirably ex- 

 posed. 



The first ova had escaped to float on the surface of the water about 

 the 16th of October ; a few hydrse still survived next day ; but on the 

 22d none. 



