CYTHERE. 171 



6. CyTHERE AURANTiA. Tab. XXI, fig. 8. 



Cythere AURANTIA, Baird, Mag. Zool. and Bot., ii, 143, t. 5, f. 26, 

 1835 ; Trans. Berw. Nat. Clnb, ii, 153. 



— M. Edwards, Hist. Nat. Crust., iii, 408. 



Shell somewhat reniform, rounded and rather promi- 

 nent on upper margin ; slightly sinuated underneath, the 

 posterior extremity rather broader than the anterior. The 

 valves are smooth, glaucous, and of a bright orange colour. 

 This species is very minute. 



^«3.— Berwick Bay; 1835. 



7. Cythere nigrescens. Tab. XXI, figs. 4, 4 a. 



Cythere nigrescens, Baird, Mag. Zool. and Bot., ii. 143, t. 5, f. 27, 

 1838 ; Trans. Berw. Nat. Club, ii, 153. 



— M. Edwards, Hist. Nat. Crust., iii, 409. 



Shell gibbosely ovate, anterior extremity rounded, nar- 

 rower than posterior, which is marked by a gibbous pro- 

 jection above and below, and is terminated by a sharp 

 point. The valves are quite smooth and free from hairs, 

 of a dirty, black colour, and translucent, showing the 

 body of the animal, which is of a very dark hue, shining 

 through. 



Hab. — Berwick Bay; not uncommon ; 1835. Dover, 

 September 1849. Arran, Boston, &c., in sand; W. C. 

 Williamson, Esq. 



8. Cythere minna. Tab. XX, figs. 4, 4 a-d. 



Bairdia siLiQTJA {vur. c. ?), T. R. Jo7ies, Entomost. of the Cretaceous 



Formatiou of England. 



Shell elongate ovate, bluntly conical on the dorsal mar- 

 gin, nearly plain beneath ; obtusely rounded on anterior 

 extremity ; sharply acute posteriorly, and narrow, the ex- 

 tremity of the shell being produced into an acute point. 

 The valves are smooth, glabrous, white, and pellucid. 

 This is totally different from any yet described, and is a 

 very distinct species ; it is the largest of all 1 have seen. 



