196 Hunting for Diatoms. 



beautiful Bupodiscus Ralfsii, with Eupodiscus subtilis ; perhaps 

 also AmpMprora lepidoptera, and other good forms. 



The sand in sheltered places, you will observe, is brown in 

 the hollows of the ripple marks. This is caused by millions of 

 diatomaceous frustules, and we must by all means take home 

 a good store of the brown sand which by washing easily yields 

 up its riches. 



Having spent so much time on the marine and brackish 

 water gatherings, let us turn inland and proceed where the tide 

 ceases to have any influence. To make sure of this, we will 

 take the rails and go to the rocky hills some ten miles dis- 

 tance. Having arrived there, let us examine, in the first place, 

 this rocky streamlet, for I see traces of a brownish covering on 

 the stones, and also some pretty long streamers. Lift the fila- 

 ments out gently, or you will get little into the bottle. On 

 examination at home you will probably detect Odontidium 

 mesodon, Himantidium undulatum, and Arcus, with Tabellaria 

 fenestrates and flocculosa. 



Proceeding a little further, we come to a little waterfall 

 trickling down the surface of the rock, and gradually finding its 

 way to the stream. The broym, velvety covering on the stones 

 looks very promising for our purpose, and if I mistake not, we 

 shall be well rewarded for our trouble in carefully collecting a 

 bottle full of the material, for we have a good gathering of the 

 beautiful Gomphonema geminatum and ventricosum mixed with 

 the minute Achnanthidium lineare. The brown mass completely 

 covering the stones in the bed of the stream is Cocconema lan- 

 ceolatum, not often found so pure. 



Let us see what causes the green colour on the surface of 

 the mud in the roadside puddle. Ah ! this is indeed a treasure, 

 for it is seldom that Navicida cuspidata occurs as perfectly free 

 from mixtures. The green colour is also remarkable, being so 

 different from the usual brown endochrome of most diatoms. 



Here is another roadside puddle left by the recent rain, 

 and see what a brown coating has grown at the bottom in so 

 short a time. At any rate we have here Diatomaccai in abun- 

 dance, though small in size, probably Nitzschia palea and Pin- 

 nularia pygmcea. 



Proceeding further inland we are supposed to be passing a 

 water-mill, and as the mill race is covered with confervoid 

 growths, let us examine some of the coating from the wooden 

 aqueduct. The brown streamers are in all probability Diatoma 

 vulgare and elongatum, and the beautiful stellate form is the 

 local Aster ionella formosa, which, by the way, seems to select its 

 habitat always in some out of the way place, such as the 

 present one in tho mill aqueduct, water tanks, and reservoirs. 



Having climbed up some distance on the hill sides, let us 



