o 



PREPARATION OF THE DIATOMACE^. 14* 



instance where a distinctly marine fossil deposit has been found 

 in England. 



For the collection of living species, Mr. Norman, of Hull, has 

 supplied us with the following hints : — The most interesting forms 

 occur in salt water, especially in shallow lagoons, salt-water marshes, 

 estuaries of rivers, and pools left by the tide. Their presence in 

 any abundance is shown by the colours they impart to the marine 

 plants to which they are attached ; or when found on mud, by the 

 yellowish-brown film they form on the surface, and which if removed 

 with a spoon will be found to be a very pure deposit. Such col- 

 lections are best put at once in bottles, with a few drops of Carbolic 

 acid ; or they may be partially dried between pieces of tinfoil. 

 Capital gatherings are also obtainable by carefully scraping the 

 brownish coloured layers from mooring posts, or the piles of 

 wharves and jetties. 



Marine gatherings contain by far the most beautiful varieties of 

 the diatomaceae ; our own coasts furnish us with some extremely 

 interesting forms, particularly Lamlash Bay, on the coast of lonely 

 Arran, Dunvegan, and various parts of the Island of Skye. But 

 for immense diversification of species the American marine 

 gatherings far outstrip us in richness, colour, and rarity. That of 

 Pensacola, in the Gulf of Mexico, contains amongst other rather 

 rare ioxuis^Aulisais pruinostis, A. coelatus^A. radiatics, A. Hardman- 

 7iican2is, ajid A. Stockhardti. The Campylodisci are C. echeneis^ 

 C. imperialism C. ccrebrecostatus^ var. speciosa, and C. imperialis. I 

 must not omit a reference to another gathering, viz.. Mobile Bay, 

 Alabama. One slide of this has been proved to contain 196 

 varieties ; and out of that number seventy-two were different 

 species of Navicula. Mr. McNeill, of Mobile, has recently dis- 

 covered in this deposit a most interesting new diatom, which it is 

 proposed to call Triphyllopelta Mobilimsis^ from its presenting 

 when dry the peculiar appearance of the form of a tri-lobed 

 clover leaf on the disc, caused by three inflations. There are no 

 rays, and the markings consist, according to my correspondent, 

 Dr. Engel, of Virginia, in coarse radiating granules resembling 

 faintly Actiiiocylus subtilis ; being both radiating and concentric. 



Mr. Ralf gives us some very useful hints as to the collection 

 of marine species and their habitats, which are as follows : — On 



