ABSTRACT It may not be uninteresting to some of your readers to know that B. cursoria is to be had in great abundance and very frequently on the Northumberland coast. Within the last few years I have made scores of gatherings from the sea-beach and rock-pools extending from the mouth of the Tyne to Cullercoats, a distance of about one and a half mile, and at least one half of those gatherings contained the curious frustules of B. cursoria. There is a large pool at the mouth of the river Tyne which is left shallowly filled with water at every tide, and is situate near the high-tide mark, from which pool I have obtained frequent gatherings of Diatomaceæ, and it is remarkable to observe how the leading species on each occasion continue to change. In a gathering made on the 18th April I found several Actinoptychus, varieties of Coscinodiscus, &c.; and on the 8th May last I obtained almost pure, and in great abundance, Nav. pseudo- libellus, n. sp., discovered by Mr. Atthey, and described by Mr. T. West in the ‘Trans, of the Tyneside Naturalists’ Field Club,’ vol. iv, p. 321. On the 16th of May I took another gathering from the same pool, and found it consisted, for the most part, of varieties of Pleurosigma, with only an occasional frustule of Nav. pseudo-libellus. On June 5th another gathering from the same locality contained almost exclusively B. cursoria so abundantly that, when viewed upon a slide, the field of the microscope presented the appearance of a racecourse with rows of frustules pushing and running in all directions. Specimens of this beautiful diatom I forwarded, living, to Mr. Norman, of Hull; Mr. Baker, of Liverpool, and Dr. Donkin, of Newcastle, the latter gentleman being the discoverer and describer of the variety. (See ‘Quart. Jour. Mic. Sei.’ Vol. VI, New Series, p. 16.)