50 
Greville^ on New Diatoms. 
distance. Instead of being conspicuously cellulate, as in B. 
pulchellttj the structure of our new species is extremely close 
and very minutely granulate or punctate. The median eleva- 
tion, in place of being simple, with concentric cellules and 
centrical spines, is 2-lobed, with a little cluster of spines in 
each, and the processes are more slender, prolonged, and 
capitate. The length of the valve before me is -0047^' ; but 
the size probably varies, as in other species of the genus. 
Biddulphia elegantula, n. sp., Grev. — Very minutely punc- 
tate ; valve, as seen in the front view, with the angles pro- 
duced into very slender, rectangular, slightly capitate horns, 
not swollen at the base ; median elevations 1 — 5, central one 
large, with 1 or 2 spines. (Figs. 12 — 14.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq. 
The nearest ally of this species is B. Tuomeyii, from which 
it differs in the almost filiform horns, not inflated at the 
base, and which form a right angle with the base of the valve, 
as in Hemiaulus. The puncta of the whole structure are also 
more minute. As in B, pulchella, Tuomeyii, &c., the num- 
ber of median elevations is variable. How this is to be ac- 
counted for is a problem at present unsolved. Does the 
friistule represented at fig. 12 ever arrive at three median 
elevations, or at five, as in fig. 13? We can scarcely venture 
to maintain that the most perfect cell before us arrived at its 
present condition without passing through the stages charac- 
terised by one and three median elevations ; yet, on the re- 
ceived theory, diatoms increase in size only in a direction 
parallel with the suture. It appears that we are driven to 
the conclusion that there must be a law of development in 
this order, the operation of which has never yet been traced. 
Length of valve, showing five elevations, •0045^^ 
Biddulphia inflata, n. sp., Grev. — Large; valve in front 
view produced at the angles into very thick, short processes, 
rectangular on the outer, beveled off on the inner side, and 
broadly truncate on the top ; median surface undulate, with 
slight elevations, divided by costse extending very little below 
the surface. (Fig. 15.) 
Hab. Barbadoes deposit, Cambridge estate ; in slides com- 
municated by C. Johnson, Esq.; extremely rare. 
I do not think that the true philosophical naturalist will 
blame me for making known these reliques of an ancient life 
because they may not be in the perfect condition we should 
look for in recent species. At the same time, while we hold 
that some allowance ought to be made for the treatment of 
genuine fosssil organisms, it would be very rash, unless in 
