PARADOXOSTOMA. 



215 



to about one half the length ; end view broadly oval. Shell smooth and polished, milk- 

 white, tipped with a small pellucid areola at each extremity. 

 Length, ^th of an inch. 

 Three or four examples of this very distinct species were found in the Bridlington 

 deposit, but too late to be figured in our lithographic plates. It has the general aspect 

 of a Paradoxostovia, but we have failed to find the mandibular aperture characteristic of 

 that species ; neither are the lucid spots visible. Moreover, there is an indistinct appear- 

 ance of overlapping of the left valve on the dorsal surface, so that we cannot but consider 

 the position here assigned to it somewhat doubtful. In lateral outline it is extremely like 

 P. abbreviatum (which species we have by some oversight omitted to include in our 

 plates), but when viewed from above is much more tumid. 



4. Pauadoxostoma ensiforme, Brady. Plate 10, figs. 27, 28. 



1868. Paradoxostoma ensifoeme, Brady. Monog. Rec. Brit. Ostrac, p. 460, pi. 



XXXV, figs. 8 — 11. 



Valves, as seen from the side, somewhat scimitar-shaped, much higher behind than 

 in front, greatest height scarcely equal to half the length, situated behind the middle ; 

 anterior extremity obtusely pointed ; posterior obliquely rounded, shghtly produced 

 above the middle ; superior margin boldly arched ; inferior gently sinuated in the 

 middle. Seen from above, compressed, ovate, with pointed extremities. Shell smooth, 

 yellowish. 



Length, ^g-th of an inch. 



Our fossil specimens dilfer somewhat in shape from the recent form as found in the 

 British islands, and are, perhaps, more exactly similar to specimens taken in the Mediter- 

 ranean, and referred by Mr. Brady to the same species. 



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



Fossil. — Scotland -. Kyles of Bute. South Wales : Cardifi' New Dock basin. 

 England : Bridlington. Ireland : Belfast New Docks, Portrush. 



5. Paradoxostoma Fischeri, G. 0. Sars. Plate XVI, figs. 23, 24. 



1865. Paradoxostoma Fischeri, G. O. Sars. Overs. Norg. mar. Ostrac, p. 96. 

 1870. — — Brady. Nat. Hist. Trans. Northumberland and 



Durham, vol. iii, p. 362, pi. xii, figs. 



1—3. 



