MALACOZOA. CEPHALOPODA. FORAMINIFERA. 319 



part, by the last turn, the cells are a little convex, with slight 

 separating depressions ; the colour hyaline-white, the dissepi- 

 ments opaque-white. Diameter nearly half a twelfth of an 

 inch. 



This very beautiful species is so regular in its cells, and so 

 transparent, that for some time I thought it a Polystomella, 

 until the inequality of its sides or disks led me to examine it 

 more closely. Montagu's Serpula concamerata seems to be 

 nearly allied to it, but that species has in its " exterior whorl 

 about nine glossy and tumid cells, of unequal size, but usually 

 a larger and smaller alternate." 



Found by me on the 10th January, on Terebella conchilega, 

 gathered on the beach near Aberdeen. 



GENUS 4. ROTALIA. P. 24, 35. 



GENUS 5. SPIROLOCULINA. P. 24, 36. 



GENUS 6. VERMICULUM. P. 24, 36. 



4. Vermiculum discif6rme. Disciform Vermiculum. 

 Shell disciform, very thin, carinate, of four turns, 



with a large, linear, oblong aperture, and a very thin 

 medial dentiform simple lamina. Disciformis, round 

 and flat. 



Shell orbicular, very thin, of four arcuate, flattened turns, 

 which are opaque, greyish or reddish-white, moderately glossy, 

 faintly rugoso-striate in the transverse direction, the outer 

 margined with a bluish white keel ; on one side all the four 

 turns apparent, on the other three ; the aperture large, direct, 

 oblong, or even linear, with the margins parallel, and having 

 a rather thick, generally reddish-brown rim, and a medial, 

 erect tooth, extending to more than half the height of the 

 mouth. Diameter a twelfth of an inch, thickness a fourth of 

 the breadth. 



This species is nearly allied to Vermiculum intortum, from 

 which it differs in its orbicular outline, in not being half so 

 thick, in its thinner keel, and much narrower mouth. 



Found by me, in December, 1842, among shell sand from 

 the Bay of Cruden, and from Ugie-mouth, sent by Mr. Alex. 

 Murray. 



5. Vermiculum plamitum. Flattened Vermiculum. 

 Shell disciform, very thin, not carinate, of four turns, 



with an ovato-oblong aperture, and a thick medial tooth, 



