I^aviculacea.] iNFtsoRTAt animalcules. 507 



DicxTOCHA Bmocidm. — Habit of D. aculeata, but with a double 

 central cell. Diameter 1 -444th. ^gina, fossil. 



D. elegans. — Pentagonal, not dentate ; angles acute but unarmed ; 

 perforated by numerous small cells, and seven central large ones, of 

 which one occupies the centre. Diameter 1-9 12th. Fossil, Caltani- 

 setta, Sicily. 



D. bipartita. — Habit of D. Cruxy but with the central cell bipartite. 

 Diameter 1 -504th. Oran, in Africa. 



D. Monodon. — Habit of D. Fibula, with four spines (aculei), but 

 each cell remarkable by a single tooth (denticulus.) Diameter l-576th 

 Richmond, in Vii'ginia. Ehrenberg described, subsequently, a species 

 \inder this same name, as being very tui'gid and hemispherical, with 

 an erect central denticle, peculiar to it ; hence he thinks it may con- 

 stitute the type of a new species. This species, or variety, was 

 found in African Guano. 



D. Saliomma. — Habit of D. s^jeculum, with six spines, and ten 

 irregular cells, of Avhich tliree are median, and seven marginal. 

 Diameter. l-840th. Oran. 



D. Hexathyra. — Habit of D. Speculum, with six spines, of which 

 five are marginal, and enclose the remaining one in their midst. 

 Diameter l-864th. Caltanisetta, Sicily. Fossil. 



D. mesophthalma. — Habit of D. Crux, and of D. Staurodon, but 

 with two denticles, one superior, the other inferior, on each marginal 

 cell. Diameter 1-3 72nd. Caltanisetta. Fossil. 



D. Ornamentum. — Presents seven spinous rays, each of the seven 

 marginal cells furnished -wdth a denticle ; one median cell. Diameter 

 l-444th. Fossil at Caltanisetta. Allied to D. septenaria. 



D. Pons. — Annular, oblong, divided into two cells by a single 

 median arch; with foui' external spines. Diameter 1 -504th. Oran. 



D. Septenaria. — Habit of D. Speculum, but with seven spines, and 

 seven marginal cells, round a single ccsntral, unarmed one ; it thus 

 approaches D. Ornamentum, furnished with teeth. Diameter l-864th. 

 Oran. 



D. staurodon. — Habit of D. Crux and of D. mesophthalma, but 

 having each marginal cell provided Avith a denticle. Diameter 

 l-576th. Eichmond, Virginia. 



D. Superstrtwta. — Quadrangular, with spinous angles, and con- 



Ll,2 



