68 Norman, on Diatomacea. 
A. vitrea, Sm. — Rare. Dredgings off Flambro^ Head. 
A. constrict a, Ehr. — Very common in brackish water. Pure 
in Victoria Dock Timber Pond. Marsh Chapel. Pure 
near Marfleet. Garrison Moat. Dairycoats, under 
Railway arch. 
A. lepidoptera, Greg. — Rare. Dredgings, Flambro^ Head. 
Amphipleura, Kiitzing. 
A. pellucida, Kiitz. — Very local. Nettleton. Very pure 
near Cottingham, Mr. Robt. Harrison. In abundance 
Risby Pond, near a submerged Willow Tree. Between 
Spring Head and Cottingham, Dr. Munroe. Very 
copious and fine, Pond, Botanic Gardens. 
A. sigmoidea, Sm. — Rare. Ascidians. 
A. danica, Kiitz. — Not unfrequent. Pure near Tetney Lock. 
Pure, Grimsby. Humber Banks. 
Navicula, Bory. 
N. rhomboides Var. /3 ^m.—interrupta, Greg — Very rare. In 
a ditch between Hedon and Paull, Dr. Munroe. Salt- 
water ditch at Dairycoats, Mr. Robt. Harrison. 
N. amphigomphus, Ehr. — Not common. Cottingham. 
Wawne. Harrogate. 
N. lanceolata, Kiitz. — Very local. Very copious in a gather- 
ing from Beverley Parks, near Woodmancy. 
N. Crassinervia, Breb. — Not unfrequent in fresh water, but 
always much mixed. Nettleton. Saltersgate. Cotting- 
ham. River Hull. 
N. cuspidata, Kiitz. — Frequent in fresh water. Spring ditch. 
Cottingham. Hornsea Meer. Hornsea Deposit. Risby 
Pond. Pure in a Puddle near Birk Cragg,^^ Harrogate 
Haltenprice. Stepney. 
iV. rhynchocephala, Kiitz. — Not unfrequent, but never abun- 
dant. Cottingham. Risby Pond. Harrogate. Hal- 
tenprice. Market Weighton Canal. 
N. Liber ) Sm. — Rare. Dredgings off Flambro^ Head. 
N. firma, Kiitz. — Not uncommon, but always much mixed. 
Risby Pond. Cottingham. Haltenprice. Spring Ditch. 
N. elliptica, Kiitz. — Very frequent, though always much 
mixed. Hornsea Deposit. Springs at Haltenprice and 
Newbald. River Hull. Reservoir Waterworks. Mar- 
ket Weighton Canal. Cottmgham. 
N. ellipsis, Sm. M. S. — Plentiful in a gathering from the 
Piers, Victoria Dock. 
N. Smithii, Breb.- — Not unfrequent in brackish water ditches. 
Bitch near River Hull. Ascidians. 
