BRIGHTWELL ON DIATOMACE. 181 
13. Amphitetras crux, n. sp.—Valve cruciform, with the 
extremities widely rounded, cellular punctate. (Pl. IX, fig. 
13, a, front view; 4, side view.) 
14, Amphitetras antediluviana (?) (Pl. IX, fig. 14.) —Mr. 
T. West believes this to be a valve of a sporangial frustule, 
of this species. Its unusuaily large size, imperfect shape 
and thinness, the cellular appearance of its punctation, and 
its occurrence among a large number of valves of the regular 
form lead to this conclusion. 
15. Biddulphia Balena.—V. ovate, elongated at the extre- 
mities; F. V. quadrate. Frustule punctato-striate. 
Zygoceros Balena, Ehr.—See Roper, on Biddulphia, 
‘Trans. Micr. Soc.’ vol. vii, p. 20. 
Arctic Regions, Cornwall Island, N. Lat. 75°, Dr. Suther- 
Jand, 
