TRANSACTIONS. 
Descriptions g/New and Raue Diatoms. Series XYI. 
By E. K. Greville, LL.D., F.R.S.E., &c. 
(Commumcated by F. C. S. Ropeb, F.L.S., &c. Read May 10, 1865.) 
(Plates V & VI.) 
Skeletonema^, n. gen.^ Grev. 
Frustules cylindrical^ equals united into a filament ; each 
frustule or joint composed of two series of large (open?) 
cellules,, terminating in striated borders, indicatingthe sutures. 
Skeletonema Barbadense, n. sp., Grev. — (PI. fig. 1.) 
Hab. Barbadoes deposit, Cambridge estate; in slides 
communicated by C. Johnson, Esq.; extremely rare. 
One of the paradoxical forms which make their appearance 
from time to time in this singular deposit. No specimen 
presenting a view of the valve has been discovered, but the 
structure and mode of fissiparous division is very obvious; 
the greater portion of each frustule is made up of a double 
series of very large, oblong, apparently open cellules, sepa- 
rated by parallel slender bars, united in the middle, end to 
end, the bars alternating with each other. At this point 
there is clearly no separation. This double series of skele- 
ton-like cellules terminate at each extremity in a somewhat 
broad striated border. The whole filament is strictly cy- 
lindrical, uninterrupted by any keel, contraction or furrow, 
and the junction surfaces are quite plain. The diameter is 
•0011''; length of frustule -0020''; length of large cellules 
•0007". 
Strangulonema, n. gen., Grev. 
Frustules united into a punctato-cellulate, cylindrical fila- 
ment; each frustule contracted in the middle, and at the 
centre of the contracted portion expanding into a nodule. 
VOL. xiii. e 
