470 



BIDDULPHIA. 



ANALYSIS OF SPECIES. 



f Valves furnished with costae 



B. pulchella. 



o 

 o 



c 



s 



a 



'S 

 3 



> 

 > 



o 



re 

 > 



Valve divided into 



several compartments 



by very deep 



constrictions. 



f All the compartments equally elevated 

 and level with the processes, which 

 are very obtuse . . . B. Regina. 



I 



Median 

 more 

 processes 

 apices . 



compartment considerably 



elevated than the others ; 



slender, with inflated 



B. Tuomeyi. 



Valves (viewed in girdle face) divided by terminal and 



median elevations into three portions, almost equal . B. aurita. 



a 

 o 



c 

 o 

 u 



re 

 > 



a 



S .2 



e~$ 



.2 v 



Si re 

 cue 



o S 



lj 



aj -5 



.i"S 



c o 

 "> fa 



Valve furnished 

 with two long awl- 

 shaped spines ; 

 median portion 

 flat or rounded. 



2 >.. 



i/) 



C 



a 



o 



B 



re o 



O ~ 



j='5 -i 



re o 



Valves with 

 cellular structure. 



Valves punctate, 

 not cellular. 



I 



Valve imperfectly silicious ; 

 not furnished with small 

 spines . . B. 



Valve very silicious, bear- 

 ing numerous small 

 spines 



B. 



Several spines placed between the pro- 

 cesses, which are abruptly diminuale 

 towards the apex. Valves broadly 

 lanceolate and inflated at the apices, 

 or trigonal 



I 



Spines 

 alterna- 

 ting, 

 with 

 robust 

 pro- 

 cesses, 

 which 

 are not 

 abruptly 

 diminu- 

 ate ; 

 valves 



not 

 lanceo- 

 late. 



Valves suborbicular, with 

 cellular girdle . 



B 



B. 



Baileyi. 

 granulata. 



Rhombus. 

 Smithii. 



o r 



re 

 > 



Spines obscure, 

 placed near the 

 centre of the 

 valve . 



Spines conspicuous, 

 submarginal, very 

 robust, with api- 

 ces often flattened 

 or bifurcated 



I 



B. lsevis. 



B. turgida. 



Valves triangular, with cells arranged in 



straight lines . . . B. Favus. 



Valves quadrangular, with cells ar- 

 ranged in concentric rows . . B. antediluviana. 



Valves furnished with vein-like lines, 

 which traverse the valve irregularly 

 and separate the angles from the 

 median portion . . . B. alternans. 



Valves without vein-like lines, with 

 medium-sized puncta in the median 

 portion, and very fine puncta at the 

 angles . . . B. sculpta. 



I. Valves furnished with costce. 



B. pulchella Gray (Arrang. of Brit. Plants, i., p. 294 

 Arl, pi. 97, f. 1-3* ; Type No. 487), plate 20, fig. 630. 



H.V.H. 



