194 



POST- TERTIARY ENTOMOSTRACA. 



5. Cytherura concentrica, nov. sp. Plate XI, figs. 7, 8 ; Plate XV, fig. 21. 



Carapace somewhat peach-stone-shaped, highest in the middle, height equal to half the 

 length ; anterior extremity obliquely rounded ; posterior oblique, produced in the middle 

 into a short, obtuse beak ; superior margin boldly arched ; inferior slightly sinuated in 

 front of the middle. Seen from above, compressed, acuminate in front, sharply and 

 strongly mucronate behind ; width less than half the length. Shell-surface concen- 

 trically striated and finely punctate. 



Length, -g^th of an inch. 



Distribution. Recent. — Shetland, Gulf of St. Lawrence. 



Fossil. — Scotland : Paisley, Barrie, Elie, Dryleys, Errol. 



6. Cytherura (?) complanata, nov. sp. Plate XI, figs. 19, 20. 



Carapace reniform, highest in the middle, height equal to more than half the length ; 

 extremities rounded; superior margin boldly and evenly arched ; inferior sinuated in the 

 middle. Seen from above, compressed, oblong, with parallel sides. Surface of the valves 

 slightly punctate, marked with a strong elevated ridge round the greater part of the 

 circumference, and with a few shallow rounded pits or areolae on the posterior portion of 

 the valves. 



Length, y^th of an inch. 



Distribution. Fossil. — Scotland: Annochie. Ireland: Woodburn. 



7. Cytherura undata, G. 0. Sars. Plate XI, figs. 9 — 15 ; and Plate XII, fig. 17. 



1865. Cytherura undata, Sars. Overs. Norg. raar. Ostrac, p. 75. 

 1868. — — Brady. Monog. Eec. Brit. Ostrac, p. 443, pi. xxxii, 



figs. 43—49, 66. 



Carapace of female subrhomboidal, greatest height in the middle and equal to rather 

 more than half the length ; anterior extremity obscurely rounded ; posterior obliquely 

 subtruncate, somewhat angulated above the middle ; superior margin forming a flattened 

 arch ; inferior nearly straight. Outline, as seen from above, elongated, subpentagonal, 

 with nearly parallel sides, width considerably less than the height, pointed in front, 

 truncate and centrally mucronate behind. Surface of the shell marked with two 

 longitudinal and three or more irregularly curved transverse ribs, the intervals between 



