LONSDALE ON EOCENE CORALS FROM N. AMERICA. 



521 



genus Astrea necessary ; 

 while in all these parti- 

 culars, the agreement 

 with the Madrepora of 

 Lamarck (ITeteropora of 

 Ehrenberg) appeared to 

 authorise the altered as- 

 signment. 



The remains of Ma- 

 drepora tubulata ? con- 

 sisted wholly of casts of 

 the exterior and of the 

 lamellae tubes. The dia- 

 meter of the branches in 

 no case exceeded three 

 lines, or that of the 

 unmagnified figure (a). 

 The tubes sprang suc- 

 cessively from the axis 

 and wholly composed it, 

 to the perfect exclusion 

 of a central, continuous 

 tube or star. As they 

 gradually diverged, they 

 separated, slightly in- 



a. Concave cast, natural size, of Madrepora 

 tubulata, exhibiting the irregular distribution 

 and convergence downwards or" the lamelliferous 

 tubes. 



b. Portion of another specimen, magnified 

 six times, linear, to give the characters of the 

 tubular casts and of the indented cast of the 

 exterior of the branch. 



creasing in diameter ; 

 and near the surface termination they suddenly bent outwards, 

 their relatively great length (three lines), and small width 

 producing the scattered distribution of the terminal stars. In 

 Guettard's figures, the branches have a greater diameter, and 

 the casts of the stars are closer. The lamellas through a con- 

 siderable portion of the tubes were apparently confined to the 

 six broader, the casts of the six narrow commencing about 

 one third from the upper extremity : both series had evidently 

 consisted of solid plates, and not of interrupted ones as in Porites. 

 So far as could be ascertained, there was no distinct, central 

 structure. The nature of the interspaces between the tubes 

 was very imperfectly exhibited, the remains being limited to a few 

 filiform processes, extending from the casts of the tubes to the 

 exterior ; but the original structure constituted a considerable 

 portion of the branches near the surface, and the lamellas tubes 

 were completely imbedded in it from the points of separation. 

 The surface casts of the branches were closely and finely punc- 

 tured, the indentations being surrounded frequently by a circle ; 

 and near the terminations of the tubes were, in some cases, casts 

 of short ribs. The production of additional lamellas tubes was 

 apparently confined to the centre. 

 Locality, — Jacksonboro'. 



