200 POST-TERTIARY ENTOMOSTRACA. 



length and nearly uniform throughout ; anterior extremity moderately and evenly rounded ; 

 posterior produced above the middle into a long and narrow beak; superior margin 

 straight or very slightly sinuated, curved downwards towards the posterior extremity ; 

 inferior straight in front, but behind the middle forming a convex curve, which 

 terminates in an acute angle behind. Seen from above, broadly ovate, greatest width 

 situate in the middle and equal to considerably more than half the length ; anterior 

 extremity rounded and minutely mucronate ; posterior subtruncate, strongly mucronate in 

 the middle. End-view triangular, with irregularly emarginate sides and broadly 

 rounded angles. Surface of the shell sculptured with very prominent and sharply cut 

 flexuous longitudinal ribs. 



Length, -^th of an inch. 



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



Fossil. — Scotland : Raised beach at Oban. Ireland : Belfast New Docks. Norway. 



18. Cytherura cellulosa [Norman). Plate XI, figs. 5, 6. 



1865. Cythere cellulosa,' Norman. Nat. Hist. Trans. Northumberland and 



Durham, vol. i, p. 22, pi. v, figs. 1/ — 20 ; 

 pi. vi, fig. 17. 



1865. CxTHERURA NANA, Sars. Overs. Norg. mar. Ostrac, p. 78. 



1868. — CELLULOSA, Brady. Monog. Rec. Brit. Ostrac, p. 446, pi. xxix, 



figs. 47—50, 60. 



Carapace of the female, as seen from the side, almost semicircular, except that the 

 postero-inferior angle is obliquely truncate, greatest height in the middle, equal to about 

 two thirds of the length ; anterior extremity rounded ; posterior obliquely truncate 

 below the middle, where it is produced into a broadly rounded beak ; superior margin 

 boldly arched ; inferior nearly straight, sinuated in the middle. Seen from above, the 

 outline is lozenge-shaped, compressed, with broadly pointed extremities and nearly 

 parallel sides, width much less than the height. The shell of the male (figs. 5, 6) is 

 obliquely ovate, much more elongated and less strongly arcuate on the dorsal margin, the 

 infero-posteal angle rounded off. Surface of the shell marked with very large, irregularly 

 angular pits, in the centre of each of which is a small elevated tubercle. 

 Length, y^jth of an inch. 



Distribution. Recent. — Norway, Great Britain, Ireland, Holland. 



Fossil. — Scotland : Gamrie, Duntroon, West Tarbert, Raised-beach at Oban. 

 South Wales : Cardiff New Dock basin. Ireland : Woodburn, Raised-beach at 

 Portrush. Norway. 



