186 POST-TERTIARY ENTOMOSTRACA. 



1851. Ctthere rhomboidea, Fischer. Abhandl. Bayerischen Akad. Wissensch., 



vol. vii, p. 656. 

 Ig53. — viRiDis, LiUjeborg. De Crustaceis ex ordinibus tribus, p. 168, 



pi. xviii, fig.s. 4 — 6 ; pi. xix, figs. 3 — 5. 

 1865. — CARiNATA, Brady. Ann. Mag. N. H., ser. iii, vol. xvi, p. 190, pi. ix, 



figs. 1—4. 

 1865. LoxocoNCHA RHOMBOIDEA, G. O. Sars. Overs. Norg. mar. Ostrac, p. 62. 

 1868. — IMPRESSA, Brady. Monog. Rec. Brit. Ostrac, p. 433, pi. xxv, 



figs. 35 — 40 ; pi. xl, fig. 4. 



Carapace of the female, as seen from the side, subrhomboidal, flexuous, greatest 

 height near the middle, equal to fully two thirds of the length ; extremities obliquely- 

 rounded, the posterior somewhat prominent above the middle ; superior margin well 

 arched, its posterior angle sinuated and obliquely truncate ; inferior convex, distinctly 

 sinuated in front. Outline, as seen from above, ovate, widest in the middle, extremities 

 equally tapering and pointed, greatest width equal to half the length. End-view very 

 broadly ovate, keeled. The shell of the male is unlike that of the female, much lower in 

 front than behind, the upper margin straight and abruptly angulated at each extremity 

 (see figure of male, L. guttata, PI. VIII, fig. 7). Surface marked with closely set 

 concentric circular punctures, which on the ventral surface run into somewhat monilifonn 

 furrows ; in the interspaces are a few distant circular papillae. The shell is dense in 

 structure, and in old specimens is covered with a thick calcareous crust, which almost 

 obliterates the surface- markings. 



Length, -^th of an inch. 



L. impressa is very abundant on most parts of the British coast at the present day, 

 ranging from the littoral zone to depths of about twenty-five fathoms ; it occurs also in 

 the more recent Glacial and Post-tertiary formations, but not in those of old date. 

 Its characters are well marked and not likely to be confounded with those of any other 

 fossil species. 



Distribution. Recent. — Norway, Great Britain, Ireland, Bay of Biscay. 



Fossil. — Scotland : Duntroon, Crinan, West Tarbert, Raised beaches at Oban and 

 Cumbrae. Ireland : New Docks at Belfast, Portrush. Norway. 



2. LoxocoNCHA GUTTATA {Norman). Plate VIII, figs. 5 — 7. 



1865. Cythere GUTTATA, Normati. Nat. Hist. Trans. Northumberland and Durham, 



vol. i, p. 19, pi. vi, figs. 9—12. 

 1868. LoxocoNCHA GUTTATA, Brady. Monog. Rec. Brit. Ostrac, p. 436, pi. 27, 



figs. 40—44. 



