HARDWICKE'S SCIENCE-GOSSIP. 



221 



and small tufts of Enteromorpha (E. compressa), 

 and thick viscous tufts of an olive-brown colour, 

 looking like confervoid algce, but which we find, 

 on examination with a low magnifying power, to be 

 diatoms (Schizonema) growing in a gelatinous 

 envelope. Let us walk on; the Enteromorpha 

 becomes thicker, and covers the mounds of the 

 rocks in long vivid light-green fringes. 



We will now examine our first rock-pool ; it is 

 about six yards distant from the beach, is very 

 shallow, and hardly three inches at its greatest depth; 

 the water in it is clear as crystal, and the surface is 

 just disturbed by the faintest ripple. The Ulva and 

 Enteromorpha grow from every part of the bed of 

 the rock-pool, except in the hollows, where there is 

 none. Growing between these seaweeds, and cover- 

 ing the bed of the pool, is a short muddy-coloured 

 filamentous-looking substance. On magnifying some 

 of this, it turns out to be diatoms growing in long 

 chains (Grammatophora marina). The margin of 

 the pool, which is very rugged in outline, is partly 

 fringed with Ulva (U. latissima), whilst on the 

 highest and most exposed portion grows the Fucus 

 (F. vesiculosus), the fronds of which hang partly in 

 the water, and are partly left dry ; it is of a dark 

 olive-colour, except at the tips, or rather receptacles, 

 which are much lighter in tint. 



The sides of the pool which are left dry are com- 

 posed of the substance resembling iron slag in some 

 parts ; in .others they are composed of tiny rounded 

 and smooth mounds, close together, having the 

 appearance of iron. They are covered with balani 

 (Balanoides) to the number of thousands. Here we 

 have an immense army; but each individual cirrhiped 

 has to receive its daily supply of food from the 

 returning sea. 



On the Ulva in the pool a periwinkle (Littorina 

 littoralis) is lazily crawling. The animal life therein 

 seems (with the exception of the balani) but scanty, 

 and we only catch sight of a single sandhopper 

 (Talitrus) ; but, on stooping, and examining the 

 pool intently, discover one of the minute Entomos- 

 traca proceeding through the water, and, skipping 

 about on the surface, a white and small podura. 



The rocks in the vicinity are composed of a grey- 

 ish and gravel-coloured sand. They are very friable, 

 and are arranged in mounds. 



Let us walk on. We leave the mounds of sandy 

 rock to our left, their summits covered with the 

 long tufts of the Enteromorpha, looking lovely in 

 the sun's light ; and, as we proceed, notice that the 

 Eucus gets much thicker, and nearly covers every 

 prominence. In some places the fronds are much 

 broader. Here and there in pools are mussels, 

 studded with young balani,. which are hardly the 

 l-32ud of an inch in diameter. We take up one of 

 these mussels and examine it. It is covered with 

 young balani on the upper surface of the shell 

 exposed to the light, whilst on the under half, or 



that portion upon which the mussel is lying, there 

 are none. 



Let us walk forward (we have taken but eight 

 strides from our first rock-pool). The Fucus (vesi- 

 culosus), which at our first pool was about three to 

 four inches long, is now in some places fully sixteen 

 inches in length. This Fucus grows in a straight 

 and narrow stem (of the length of six inches) from 

 the rock. It then divides into three bunches of 

 fronds, each composed of two flat branches, which 

 again are bifurcate, and terminate in the recep- 

 tacles. 



The Ulva latissima is now growing together 

 with the Fucus, on which a good many periwinkles 

 are crawling. At twenty-four yards from the beach 

 we find our first tuft of the seaweed Polysiphonia , 

 of a lovely purple hue, growing in a shallow pool of 

 three inches in depth, and in a position facing the 

 east. Some Ulva is growing from the Polysiphonia, 

 the tuft of which is nearly dry at the place of its 

 attachment to the rock, whilst the ends thereof 

 hang freely in the water. Sprawling over the 

 branches of the Polysiphonia in a very slow and 

 listless manner, are several of those queer-looking 

 objects, the Pycnogons (Nymphon gracile). We 

 move the tuft very gently. As we do so, numerous 

 sandhoppers and small Crustacea start from it, and 

 immediately underneath it is revealed to us a 

 mussel {Mytilus edulis), his beautiful gills stretched 

 to their fullest extent, and we may presume he is 

 now actively engaged in taking in his morning meal. 

 Immediately under the mussel, and partially im- 

 bedded in the deposit, is a small oyster-shell, of 

 which we get a lateral view. On its upper edge is 

 an anemone {Actinia chiococca), whilst on its under 

 surface, and seen in profile, are full-grown balani 

 (Balanoides), whose cirrhi, we can see, are working 

 rapidly. 



At forty yards from the shore we find some very 

 fine purple tufts of Polysiphonia, growing on both 

 the east and west side of the pool. Resting on its 

 branches, and motionless, is the crustacean Idotea 

 tricuspidata. We have here also a very thick and 

 bushy mass of olive-coloured alga, having the 

 character of conferva, which looks, at first sight, 

 very much like Schizonema. It is growing from the 

 flat frond of a piece of fucus in the water. We 

 place a small tuft of the Polysiphonia in our zoo- 

 phyte-trough, and magnify it with our half-inch 

 objective. Its branches are crowded with diatoms,, 

 and some large orange-coloured rotifers are 'gliding 

 about. To the naked eye they appear about the 

 1-2-lth of an inch in length. 



At an estimated distance of one hundred yards 

 from the shore we find rocklimpits (Patella vulgata) 

 and the zoophyte Sertularia geniculata growing 

 from a frond of fucus. The mussels are now very 

 numerous, and close together in the gulleys between 

 the rocks, and are affixed by their byssus to the 



