for the Microscope. 89 



top; the inner lateral broader, and also recurved; the two 

 outer lateral series more or less conical. 



694. PALATE OF MuD-SHELL(Zz>rt//<m stagnalis}. Teeth 

 in numerous series, entirely or nearly uniform. 



FORAMINIFERA. If common chalk be carefully 

 broken up and washed, the shells of several species of 

 fossil Foraminifera may be obtained, and these will con- 

 stitute a very attractive series of microscopic objects. 

 Some of these we have figured and enumerated. 



695. OBTUSE BULIMINA (Bulimina obtusa). This is 

 one of four species, belonging to the same genus, which 

 are to be found in English chalk. The outline is very 

 similar to that of some of our small land-shells. (PI. IX., 

 fig. i.) 



696. MURCHISON'S BULIMINA (Bulimina Murchisom- 

 anci), This is a broader, shorter, and more acutely 

 pointed form than the preceding, and is found in chalk 

 from the neighbourhood of Gravesend. 



697. SLENDER TOOTHSHELL (Dentalina gracilis). This 

 long, slender, and delicate shell is also from the chalk. It 

 is liable to be broken or washed away in the cleaning, un- 

 less that process is conducted with considerable care. 



(PI. IX., fig. 2.) 



698. RIBBED TOOTHSHELL (Dentalina snlcata). This 

 is a more common form of Toothshell than the last, from 

 which it may be known by its longitudinal ribs, which 

 give a stellate appearance to an end view of the shell. 



699. PRICKLY TOOTHSHELL (Dentalina aculeata). The 

 distinctly moniliform arrangement of this shell, and its 

 surface studded with little acute processes, serve to dis- 

 tinguish it from its allies. It occurs in Gravesend chalk. 

 (PI. IX., fig. 8.) 



700. WHEELED CRISTELLARIA (Cristellaria rotulata) 

 has more the form of a minute Nautilus than any other 

 chalk species. It may be obtained from washings of 

 Sussex chalk, and is the only British species of the genus 

 found in the chalk. (PI. IX., fig. 3.) 



