NoRMAN_, on Diatom acece. 
157 
P. peregrina, Ehr. — Very frequent in brackish water. Stone- 
ferry. Tetney. Humber Banks^ very frequent. Copious 
and nearly pure in a ditch near River Hull^ above Stone- 
ferry. 
P. acuta, Sm. — Very frequent in fresh water. Cottingham. 
Pond at Skirlaugh. Risby Pond. Driffield. Wawne. 
Market Weighton Canal. Spring Ditch. Beverley. 
P. direct a, Sm. — Local. Frequent in a salt-water gathering, 
Grimsby. 
P. radiosa, Sm. — Very frequent in fresh and brackish water. 
River Hull, pure. (Nottingham. Pure at Harrogate. 
Haltenprice. Pure in a Spring, Cottingham. Hornsea 
Peat Deposit. Reservoir Waterworks. 
P. gracilis, Ehr. — Very frequent in brackish and fresh water. 
Marfleet. Humber Banks. Pure in a ditch near River 
Hull. Tetney. Saltersgate. Spring Ditch. 
P. viriclula, Sm. — Very abundant in fresh water. Wawne. 
Killinghall. Abundant near Cottingham. Near Stone- 
ferry. Very pure near '^^New Village" Cottingham. 
P. Cyprinus, Ehr. — Very abundant in salt and brackish water. 
Dairycoats, under Railway arch. Humber Banks, fre- 
quent. Marsh Chapel. Tetney. Grimsby. Very good 
in a ditch near the River Hull. 
P. divergens, Sm. — Rare. Cottingham, near Mr. Harrison^s 
Grounds. Ditch near Springs, Cottingham. 
P. stauroneifo7inis, Sm. — Not unfrequent in freshwater. Co- 
pious in a gathering, Skirlaugh. Nettleton. Reservoir 
Waterworks. Harrogate. Cottingham. Spring Ditch. 
P. Johnsonii, Var. |3 Sm. — Copious in a gathering from the 
Piers of the Victoria Dock. 
P. gibba, Ehr. — Rare in fresh water. Saltersgate. Risby 
Pond. Cottingham. Plaltenprice. 
P. Tabellaria, Sm.— Rare. Rocky stream, Saltersgate. 
P. mesolepta, Ehr. — Not unfrequent in fresh water. Boggy 
ditch, Saltersgate. Haltenprice. Hornsea Deposit. Be- 
verley Parks. 
mesolepta Var. with stauros. — Fresh water. Risby Pond. 
Harrogate. 
P. interrupta, Sm. — Not common. Nettleton. Wawne. 
Harrogate. 
P. interrupta, Sm. Var. j3. — Rare. Clay Pits, Nettleton. 
P. borealis, Ehr. — Rare. Soil from Benningholme Carrs. 
Market Weighton Canal. 
P. hemiptera, Sm. — Rocky stream, Saltersgate. 
P. gracillima, Greg. — Rare. In rocky stream, Saltersgate. 
P. Polyonca, Breb. — Very rare. In a pond in the wood at 
Nettleton. 
