DIATOMACEAE. 339 
Pinnularia divergens, Sm. 
Marsh at the eastern side of Lancresse: a rather small form 
resembling Smith’s P. s/auronetformts, var. [2. 
Pleurosigma arcuatum, Donk. 
A sprinkling of specimens occurred in a gathering I made in 
1889 from a small roadside marsh at Bordeaux which has since 
been filled with quarry rubbish. Dr. Donkin aptly compares the 
curved rostrate apices of this diatom to the bill of a curlew. 
Pleurosigma macrum, Sm. 
One fine specimen in a rock gathering from Cobo. 
Pleurosigma prolongatum, Sm. 
Pleurosigma formosum, Sm. 
Cobo peat deposit, one imperfect specimen. The colour of the 
dry valve is described by Smith, Ralfs, Rabenhorst, and others as 
pale chestnut brown: but in scores of gatherings containing this 
beautiful diatom which I have made at various times in Hampshire, 
Devonshire, and Cornwall, the dry valve has invariably been of a 
deep blue colour. 
Pleurosigma decorum, Sm. 
Petit Bot Bay, abundant. Perelle Bay and Bordeaux, rather 
common. Salerie, a few. 
Pleurosigma rigidum, Sm. 
More or less common in low-water gatherings from all parts of 
the coast. Petit Bot Bay, occasional and rather small. 
Pleurosigma validum, Shadb. (?). 
Frequent at Cobo and Petit Bot Bay at extreme low water: more 
rarely at Saints Bay, Moulin Huet, Bordeaux, and Perelle. A large 
and nearly straight species with broad apices, very slightly flexed 
median line, and delicate striation. It agrees exactly with the 
species described under this name by Ralfs (in Pritchard’s Jnfusoria, 
1861), but I have seen no figure. 
Pleurosigma strigosum, Sm. 
Common in a mixed scraping of rocks and corallines from low 
water at Cobo. ) 
Pleurosigma naviculaceum, Breb. (P. transversale, Sm.) 
Rather common in low-water gatherings from all parts. 
Pleurosigma elongatum, Sm. 
Frequent in a gathering from a small marsh at Bordeaux. 
Pleurosigma intermedium, Sm. 
