Resting Eggs, or Staioblasts of a Plumatella. 271 



BESTING EGGS, OR STATOBLASTS OE A 

 PLUMATELLA. 



BY HENEY J. SLACK, E.G.S. 



{With an Illustration!) 



On the 29th June, 1861, the day being fine and hot, my atten- 

 tion was called to an entangled mass floating in the large pond 

 at the bottom of Hampstead Heath, behind Jack Straw's Castle. 

 On drawing a portion of it ashore by means of a landing hook, 

 it was evident that the capture consisted of fresh water polyzoa. 

 The coencecium (common house) or polypary was very compact, 

 and composed of numerous tubes, having a multiplicity of 

 openings ; but none of the branches projected far from the main 

 stem, which clung to, and surrounded the long fine stalks of 

 some defunct water plant. This mode of growth was more 

 like that of certain marine forms of polyzoa than of any which 

 I had been in the habit of finding in ponds or streams ; and 

 as the ' pocket lens could only afford general evidence of 

 relation to the Plumatella family, I hastened home to call the 

 microscope to my aid. A branching tuft of the polyp tubes 

 was soon placed in a zoophyte trough, illuminated by Wenhanr's 

 parabola, and viewed under a two-thirds objective. The effect 

 was splendid. The living flowers expanded freely, the tentacles 

 assumed a pearly lustre, and the vibrating cilia glowed like 

 scintillating jewels as they caught the light. It was evident 

 that the lophophore or " crest-bearer/' from which the tentacles 

 proceeded, was crescent- shaped, or, as it is technically termed, 

 crescentic, and not circular ; and the tubes, taken separately, bore 

 a strong resemblance to those of Plumatella repens ; but I had 

 never seen or read of this species forming a colony in such a 

 dense enveloping mass. Of course, a reference to Professor 

 Airman's splendid work on the Polyzoa was my first resource, 

 but not finding the difficulty solved, I bottled up a good speci- 

 men, and sent it by post to that able naturalist's address. Un- 

 fortunately, the creatures did not reach him alive, and this 

 circumstance, together with a pressure of other engagements, 

 prevented his settling the point, whether they could be identified 

 or not, with any recorded species. My own impression was in 

 favour of considering them as varieties of P. repens, as the 

 tubes had neither furrow nor keel, and I noticed no characters 

 that assimilated them more closely to any other member of the 

 Plumatella family. 



I gave my specimens abundance of water in a large 

 glass jar, in which some anacharis and myriophyllum were 

 growing, and left them in an airy room, where I hoped they 



