CYTHERELLA. 



65 



on these differences, are shown to be 26 forms of Group I, having an even and smooth 

 surface, a more or less elliptical outline, and a cuneiform profile or edge-view ; and 

 6 having a lanceolate (not cuneiform) profile, and approaching Bosquetia in this respect. 

 In the same group 13 have a punctate surface to their smooth, more or less elliptical 

 valves, with wedge-shaped profile ; and 2 have a reticulate ornament. In Group II the 

 valves, more or less oblong, have an uneven surface; 13 of them are smooth; 1 granu- 

 lose ; and 8 punctate. The grouping of these little organisms does not appear to be 

 at all coincident in detail with their " range in time." 



Synoptical arra?igement of the Cytherella; and Bosquetia, according to the Shape and 

 other features of their Carapace-valves. 



rofile. 



CYTHERELLA and BOSQUETIA. 



I. Surface even. A. Smooth. 

 § 1. Outline elliptical, more or less ovate, and suboblong; with cuneifon 



1. Broadly elliptical. Cytherella brevis, Jones, 1870 . . Carboniferous. 



2. Elliptical-ovate. Lonsdale in Lyell, 1838 ; Cytherella ovata, 



Roemer, 1840? 1841; Reuss, 1845; Jones, 1848; Reuss, 



1850 ; Bosquet, 1854. The outline varies in the several figures Cretaceous. 



3. Elliptical. Cytherella complanata, Reuss, 1845 (narrow), and 1854 



(elliptical) ..... Cretaceous. 



4. Elliptical. Cytherella Leopolitana, Reuss, 1850 (subelliptical) ; 



Reuss, 1854 ..... Cretaceous. 



5. Subelliptical. Cytherella kevis, G. S. Brady, 1868 . . Recent. 



6. Elliptical; with pit. Cytherella compressa, Miinster, 1838; Reuss, 



1849: Bosquet, 1852; Jones, 1856; Eggcr, 1858. Outline 



varies in the different figures .... Tertiary. 



7. Elliptical and pointed (ovate). Cytherella elongata, Reuss, 1845 . Cretaceous. 



8. Subelliptical. Cytherella lata, G. S. Brady, 1880 . . Recent. 



9. Subovate or subelliptical. Cytherella fabacea, Bornemann, 1855 . Tertiary. 



10. Subovate. Cytherella nuciformis, Jones, 1850; Reuss, 1854; 



Richter, 1855 and 1867; Geinitz, 1861 . . . Permian. 



11. Subovate or subelliptical ; with pit; margined. Cytherella Londi- 



nensis, Jones, 1856 ..... Tertiary. 



12. Suboblong. Cytherella truncata, 1 Bosquet, 1847 ; Jones, 1848 . Cretaceous. 



1 For the truncata of G. S. Brady, 1869, see further on. 



