CYTHERE. 173 



indentations visible, which give it a kind of wrinkled ap- 

 pearance at that part. 



Hub. — Devonshire, VV. C. Wilhamson, Esq.* Tenby, 

 T. Rupert Jones, Esq. 



11. Cythere acuta. Tab. XXI, fig. 5. 



Shell oval, convex, acute at both extremities, which are 

 nearly of equal size, of a pale, horny hue, smooth, glaucous, 

 transparent ; upper margin considerably arched and 

 rounded, the inferior one slightly so. In shape it some- 

 what resembles a grain of oats. 



Hab. — Arran, in sand ; W. C. Williamson, Esq. 



12. Cythere pellucida. Tab. XXI, fig. 7. 



Shell oblong, reniform, narrow; both extremities rounded 

 and nearly of the same size with each other ; pellucid, and 

 of a white colour. The surface at fu"st appears smooth 

 and shining, but when examined with the microscope it 

 is seen to be minutely dotted or punctated. 



Hah. — Boston, in sand ; W. C. Williamson, Esq. 



13. Cythere impressa. Tab. XXI, fig. 9. 



Shell oval, very convex, of much the same size at both 

 extremities. The surface of the shell is covered with im- 

 pressed puuctations, and the colour is of a dull blackish 

 hue. The substance is of considerable thickness. 



Hah. — Torquay, in sand ; W. C. Wilhamson, Esq. 



14. Cythere quadridentata. Tab. XXI, fig- 2. 



Shell oval oblong, narrower at one extremity than the 

 other ; the longer extremity (the posterior) rounded and 

 slightly crenulated or toothed ; the narrower extremity 

 (anterior) produced and terminating in four distinct 



* I am glad of this opportuuity of acknowledging the kind and liberal 

 manner in which Mr. Williamson has placed his specimens of Ostvacoda in 

 my hands for description. 



