5 



ASTEROLAMPRE^E. 



W. insignis Panl., fossil at Ananino, Russia (fig. 243), drawn from my 

 photograph of Dr. Pantocsek's specimen. 



This genus appears to me to be very closely approximate to the preceding. 

 It will be necessary to examine a larger number of quite perfect valves to 

 identify or differentiate the two genera definitely. 



TRIBE XXIV. ASTEROLAMPRE/E. 



Table of Genera. 



"Valve furnished with strong internal costae, united to one another at the centre and 

 sides by a robust internal lamina, centre hyaline 



( Valves hyaline, angular or circular, without costas or straight rays not enlarged 

 near the margin or near the centre, and not touching the margin 



Arachnoidiscus. 



. Liostephania. 



fDisc radiated, punctate, cellular or granular, with centre granular, not 

 stellate, with marginal portion divided into numerous compartments by 

 enlarged costae in the form of spokes of a wheel 



f Valves inflated, hyaline or punctate, with centre sometimes stellate, 

 rays linear, more or less bifurcated and somewhat irregular ; inter- 

 spaces hyaline or with flexed or sinuous lines 



f Valves hyaline, divided by simple rays ; centre hyaline or granu- 

 lar, reticulate, or finely punctate . 



Gyroptychus. 



Cladogramma. 



2^ 



o 



o -i 



a 



,- 





be 



a 



o 







o . 

 c P. 



IT, 



,0 



f Rays simple, straight, never reaching to the centre ; 

 puncta more or less large and scattered 



Mastogonia. 



Stietodiscus. 



Rays irregular both as to length and division, often 

 divided dichotomously ; valves with cells small, uni- 

 form throughout the surface . . . Radiopalma. 



o B 



O 



O 



V 



a o 



g as 

 m k 8 



ST 



Rays straight, marginal portion of the valve 

 punctate, and traversed by sectors, radiant, 



verv narrow 



Stelladiscus. 



Rays curved like the letter S ; valve completely 



hyaline 



. Gyrodiscus. 



rt 



2 a 



3 'o 



S ! 



< rt 5 



J - < 



E ; 

 p 



h^ 

 <%\ 



a/5 I 



o ra 



as w 



o 



Valve with hyaline area, divided by straight 

 rays, arising either from the centre or from a 

 central rosette and terminating at the base in 

 areolated marginal segments ; such segments 

 being formed by the subdivision of the margin, 

 aided by the continuation of the hyaline area Asterolampra. 



Valves as in the preceding, but with two com- 

 partments approximate and one ray narrower, 

 interrupted, not going beyond the centre . Asteromphalus. 



05 



I 



Valve showing robust septa, radiant, 

 concentric circles of cells 



and with 



Asterodiscus. 



I I I I 



I Valve as in Asterolampra, but with only two rays and 



I these inflated near the central rosette . . Rylandsia. 



