W. J. CAIRD. 



coloured weed fucus nodosus. On it too are hairs, take a share and 

 pop them into your bottle, for you have sertularia pumila. Hullo ! 

 there's a hermit crab in a big whelk shell catch him. Oh, you say, the 

 shell is prickly like a hedgehog, only the prickles are not so long. Good 

 man ! keep him crab and all into your bottle, quick, for you have got 

 one of the simplest and prettiest sights you have ever seen hydractinia 

 echinata. Let's look at your bottle just look at all the lovely white 

 hydra you have there each complete in itself, and yet not complete 

 save altogether. Now, I think we have enough for a start. Before we 

 go just put that little piece of red weed ptilota plumosa with its coral-like 

 incrustation into your bottle also. It is a polyzoa meinbranipora 

 inembranacea. It the empty cells makes a lovely slide for the micro- 

 scope when mounted oji a dark ground, and lighted from above. 



Now, let's keep together and we will talk of these on the homeward 

 journey. The first one we got on the tangle obelia geniculata is the 

 common type of its class. The stalk rises from the stolon (root you 

 may call it) and goes up by joints like a piece of bamboo, bent at every 

 joint out of the straight. From the joint rises a stalk of 6 or 7 rings, 

 and on the top is a bell-shaped cup, with a smooth edge. Inside the cup 

 is your hydra-looking creature. On examination you will find it has 

 tentacles, and a central portion or mouth. If you cast it over in your 

 mind you have seen this form of polype before true, very much enlarged 

 the sea anemone. 



The sertularia rugosa also arises from a stolon, is likewise zigzag, 

 but the cups are very much wrinkled and have no stalks, /.., the cups 

 are sessile. The same sort of polype is inside. Sertularia pumila is 

 another of this family and differs from the former by having no wrinkles 

 on the cup, and the cups are sunk into the stalk and come out in pairs, 

 one on each side. 



Hydractinia echinata has a stolon, but every here and there the 

 stolon rises up in horny points to give protection to the animal which 

 has no stalk to protect it. If -it had been a little later in the season you 

 would have found clear jelly-like swellings on the first three. From 

 these issue miniature jelly-fish or medusoids, which swim about freely, 

 and about August or September next settle on some likely spot and 

 change back into hydroids. Thus in the sea as well as on the land we 

 have an alternation of species. 



But the reproductive organ on hydractinia echinata is a modified 

 polype, and not a specialised organ as in the others. 



