22 Searlf. , The Pond and its Inhabitants. [vj."^xxxiv 



dweller it breathed by means of ^ills. but the drap:on-fly has 

 now become a creature of the air, and will now breathe through 

 spiracles placed along the sides of its body. At what period 

 of its history this change in the breathing tubes occurs is still 

 obscure. Its body having dried and its four beautiful wings 

 thoroughly hardened, the insect essays its first flight, and soon 

 after it mav be seen darting swiftly through the air, capturing 

 and devouring its prey without pausing in its rapid flight. After 

 a brief courtship the female visits a pond, and, resting on a water- 

 plant, thrusts her abdomen under the water and attaches her 

 eggs to the stem or leaves of the plant, her life-work being then 

 accomplished. 



Moss Animals. 



The term "moss animals" has been applied to that group 

 known to the zoologist as Polyzoa (Gr. polus many, zoon 

 animal) — compound animals that spread themselves over the 

 surface of stones, roots, and stems of water-plants, the most 

 familiar example, perhaps, being the sea-mat, found in rock 

 pools around our coasts. Relatives of these, to which no 

 common name has been given, are to be found in many of the 

 ponds and streams in the vicinity of Melbourne, and, though 

 well knowTi to the initiated, who know where and how to look 

 for them, are never seen by most people, though they are 

 particularly well adapted for nature study. Only two fresh- 

 water genera have been found in Victoria up to the present, 

 though it is quite probable others exist here waiting discovery 

 by the observant pond-hunter. The known genera are 

 Plumatella and Fredricella. 



Plumatella is the more common of the two, and is found in 

 many of the pools that aboimd along the valley of the Yarra. 

 A favourite place for it was the lagoon on the left-hand side 

 of the bridge over the Yarra at Heidelberg, where the sub- 

 merged branches of the old willow trees were thickly covered 

 with this beautiful animal. The individiials of the colony are 

 quite large enough to examine with a pocket lens, and in a yoimg 

 colony are transparent enough for the process of digestion, 

 &c., to be observed within. If we place a small colony of 

 Plumatella in a watch glass with some water and examine it 

 under a pocket lens, or better, a dissecting microscope, we 

 will be able to learn much about its structure and habits. The 

 shock of moving the colony to the watch-glass has caused all 

 the polypides to retract within their cells, which, we see, are 

 oval-shaped bodies attached to a stem of leathery consistency. 

 This stem is called the crenaeceum (meaning " common house "), 

 and unites the whole colony. If the watch-glass is allowed 

 to remain still for a few moments the animals recover from 



