COLLECTING DIATOMS. 



33 



Algse and Corallines found growing on them. These, on being cleaned, 

 often yield splendid results. Many of the most beautiful and rare 

 species of Campylodiscus have been obtained from this source. The 

 Californian Haliotus shell is almost certain to yield the fine Aulacodiscus 

 Oregonus, Arachnoidiscus, Hyalodiscus cervinus, and Biddulphia Roper i; 

 while the Haliotus from New Zealand will probably furnish the rare 

 Aulacodiscus Beeverice and Macraeatius. 



" The West Indian Strombus shells invariably yield beautiful forms, 

 such as Campylodiscus eccltsianus, ambiguus and imperialis. 



" Vessels with guano are worth visiting. The Peruvian guano, when 

 properly prepared, yields the magnificent Astcrolampras and Aulacodiscus 

 scaber ; while the Bolivian is even richer in fine things, such as the 

 superb Aulacodiscus formosus and Comberi. Californian guano yields, 

 among an infinite variety of forms, many of great beauty and rarity, 

 such as Aulacodiscus margaritaceus and Biddulphia Tuomeyii. Algoa Bay 

 is frequently rich in Aulacodiscus Petersii ' ; and finally, the Ichaboe 

 guano, Eupodiscus Ehrenbergii, and other good things. 



" The old mooring anchors and cables, which are now lying on the 

 quay, are covered with a marine incrustation, which, on examination, 

 will be found deserving of notice. 



"We will now take a stroll towards the timber ponds, where the 

 timber often remains afloat for years. Here we see ample traces of 

 the objects of our search. The sides of the logs seem quite covered 

 with a tangled mass of the filamentous forms ; but before we bottle 

 up any of them, let us collect with the spoon some of the brown 

 pellicle which covers the surface of the water. This proves to be a 

 very pure gathering of Amphiprora constrida. Then let us collect some 

 of the green Ulva and Enteromorpha, growing on the sides of the timber, 

 which seems so brown and furry. With the Coddington lens we find 

 the brown tint is owing to a dense parasitic growth of Achnanthes 

 longipes and brcvipes. The long brown filaments are principally Melosira 

 nummuloides and Borren'i, with Schizonema crucigerum and Dillwynii, 

 mixed with Bacillaria paradoxa, shooting into long filaments, then 

 suddenly retreating until the filament is closed again, one frustule 

 sliding past the other in a most marvellous manner. By the way, 

 this species will live, and even thrive, quite well in perfectly fresh 

 water. Mixed with the Bacillaria, we find Nitzschia Sigma, and other 

 free forms. 



"The wooden piers running out into the river are brown, with a 

 covering of Homceocladia siqmcidia, Pinnularia /o/insonii, and Navicula 



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