150 POST-TERTIARY ENTOMOSTRACA. 



marked as to leave no doubt of its identity ; we had indeed described it in MS. as a dis- 

 tinct species years before its discovery in the living state by the Rev. A. M. Norman. We 

 have ourselves still more lately seen many recent specimens from the Gulf of St. Law- 

 rence. 



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



Fossil. — Bridhngton . 



12. Cythere gibbosa, B. 8)' B. Plate XVI, figs. 16—18. 



1869. Cytheke gibbosa, Brady and Robertson. Ann. and Mag. N. H., ser, iv, vol. iii, 



p. 368, pi. xxi, figs. 1 — 3. 



Carapace oblong, subtriangular or subtrapezoidal, highest in front of the middle, 

 height fully equal to half the length, anterior extremity obliquely, posterior evenly rounded j 

 superior margin prominent in front of the middle, thence sloping steeply to the front, 

 more gently and almost in a right line backwards, inferior margin straight or gently 

 convex ; seen from above, subovate, widest near, or a little in front of, the middle, width 

 considerably less than the height, extremities acuminate, end view broadly ovate. Shell 

 rather thin and fragile, smooth and shining, slightly punctate and papillose, the ventral 

 surface greatly depressed in the centre, forming a slight longitudinal fossa. 

 Length, 6-5 th of an inch. 



Distribution. Becent. — Great Britain and Ireland. 



Fossil. — Portrush, Ireland. 



13. Cythere convexa, Baird. Plate III, figs. 14 — 17. 



1850. Cytheke convexa, Baird. Brit. Entom., p. 174, pi. xxi, fig. 3. 



1856. — PUNCTATA, Jones. Monog. Tertiary Entom., p. 24, plate ii, figs. 



b — d,f — h (not a and e). 

 1868. — CONVEXA, Brady. Monog. rec. Brit. Ostrac, p. 401, pi. xxix, figs. 



19 — 27; pi. xxxix, fig. 4. 



Carapace of the female, as seen from the side, almost semicircular, greatest height 

 in the middle and equal to more than half the length. Anterior extremity broadly 

 rounded, posterior produced below into a somewhat angular beak ; superior margin very 

 boldly arched, highest in the middle, inferior gently sinuated in the middle and convex 

 behind. Outline, as seen from above, oblong-ovate ; greatest width in the middle, and 

 equal to less than half the length ; extremities obtusely pointed ; end view broadly ovate, 

 pointed above and below. The two valves are very unequal in size and dissimilar in shape, 

 the left being the larger and overlapping the right considerably, especially on the dorsal 



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