§ X. SUPPLEMENTARY. 



221 



[The following have been accidentally omitted from their proper positions in the 

 descriptive portion of this Memoir.] 



42. Cythere Robertsoni, Brady. 



1868. Cythere Robertsoni, Brady. Ann. Mag. N. H., ser. iv, vol. ii, p. .33, pi. iv, 



figs. 5, 8—10. 



Shell of the female compressed, subcuneiform, much higher in front than behind ; 

 greatest height situated in front and equal to somewhat more than half the length; 

 extremities obliquely rounded ; anterior broad, posterior narrowed ; superior margin 

 straight, sloping steeply from before backwards ; inferior sinuated in the middle, curved 

 upwards behind. Seen from above, compressed, oblong, with nearly parallel sides ; 

 anterior extremity acuminate, posterior suddenly tapered and obtusely pointed ; width 

 much less than the height. End-view ovate, widest in the middle. Shell of the male 

 much narrower ; surface of the shell covered with closely set angular pittings. 

 Length, -g^nd of an inch. 



Distribution. Becent. — Great Britain, Ireland, Norway. 



Fossil. — Scotland : Loch Gilp. Norway. 



20. Cytherura Robertsoni, Brady. 



1868. Cytherura Robertsoni, Brady. Monog. Rec. Brit. Ostrac, p. 444, pi. xxxii, 



figs. 16—18. 



Carapace of the female, as seen from the side, subovate, produced into a lateral ala 

 behind the middle of the ventral margin ; height equal to more than half the length ; 

 anterior extremity rounded, posterior slightly produced in a rounded manner above the 

 middle. Superior margin gently and evenly arched, inferior slightly sinuated. Seen from 

 above, subrhomboidal, widest behind the middle, extremities slightly mucronate; width 

 equal to about two thirds of the length. End-view broadly triangular, with much pro- 

 duced basal angles ; width greater than the height. The shell of the male is more 

 elongated, more sinuated below, and has less prominent lateral alse. Shell-surface very 

 distinctly and regularly marked with a raised reticulation ; ventral surface longitudinally 

 striated. 



Length, :^2-nd of an inch. 

 Distribution. Becent. — Great Britain. 



Fossil. — Scotland : West Tarbert Silt. Canada : Saxicava Sand, Montreal. 



