344 
H. bilobata. (Sm.) Occurring in most of the Breydon gather- 
ings, but not plentifully. 
hi. plana. (Sm.) Found with the above, but rare. 
hi. virgata. (Roper.) Sand gatherings, Hunstanton and Wells. 
N. spathulata. (Sm.) Very rare — in sand gatherings from 
above localities. 
H. socialis. (Greg.) I have detected a few frustules occasionally 
in the Hunstanton sand gatherings. 
N. panduriformis. (Greg.) Wells and Hunstanton sands — rare. 
Genus Tryblionella Smith. 
T. scutellum. Sm. Very rare — I have only found this in one 
of the Breydon gatherings. 
T. gracilis. Sm. Frequent in the Breydon gatherings ; more 
rarely in those from Hunstanton, Wells, and Yarmouth. 
T. punctata. Sm. Frequent with the above. 
T. angusta. Sm. Cossey, Whissonsett, Weston. 
Genus Homeocladia Agardh. 
H. sigmoidea. (Sm.) Rare — in a gathering off the piles of 
Yarmouth Jetty. 
Family VI — ACHhTANTHEJE. 
Genus Cocconeis Ehrenberg. 
C. scutellum. Ehr. Growing on Zostera marina, Yarmouth ; 
sand gatherings, Hunstanton. 
C. pediculus. Ehr. Ormesby, Whissonsett, Heigliam Causeway. 
C. placentula. Ehr. Horning, Hickling, Tittleshall, Whisson- 
sett. 
Genus Achnanthidium Kutzing. 
A. lineare. (Sm.) Rare — in a fresh-water ditch, Yarmouth ; 
a few isolated frustules in the Ormesby gatherings. 
A. ventricosum. (Ehr.) Rare — in moss from Osier Car, 
Heigham. 
A. flexellum. (Breb.) Ormesby, Flordon, Horning. 
