PALEOZOIC CORALS AND FORAMINIPERA. 93 



ries ; the tubes are imbedded in a uniform cellulose tissue, from 

 which the buds or young tubes seem to arise whenever the di- 

 stance becomes great between any two cells, but the young tubes 

 do not seem traceable into the old. The coral referred to by 

 Dana {Acervularia Baltica of Lonsdale in the ' Silurian System ') 

 as the type of his genus Arachnophyllurriy I find to have the 

 cell-tubes transversely septate, though not well shown in Lons- 

 dale^ s figure — the latter genus has therefore no peculiar cha- 

 racters — the cellular structure of the rays being common to 

 several corals. 



Sarcinula tuberosa (M'Coy). 



Sp. Char. Corallum forming large shapeless masses, the upper 

 surface covered with irregular tuberose projections, separated 

 by flat or concave spaces, and each having a depressed tubular 

 centre 1 line in diameter, average distance between the centres 

 5 lines ; from the margin of each centre about thirty slightly 

 sigmoidal, very delicate laminse radiate to the adjoining ones, 

 generally without interruption, the radii connected by nume- 

 rous small transverse vesicular plates : vertical section, centres 

 forming nearly vertical and subparallel cylindrical tubes, with 

 close transverse septa, connected by exceedingly fine uniform 

 cellulose structure, which seems formed of small depressed 

 cells arranged nearly in horizontal layers with a double curve 

 conforming to the projections of the surface : horizontal section 

 shows the tubular centres connected by a minute uniform 

 cellular structure with a scarcely appreciable radiation. 



This strongly resembles the so-called Acervularia Baltica of 

 the ' Silurian System.' 



Kare in the carboniferous limestone of Derbyshire. 

 [Col. University of Cambridge.) 



Sarcinula placenta (M^Coy). 



Sp. Char. Corallum forming tabular masses about 1 inch thick ; 

 under side with small, concentric, imbricating undulations of 

 growth and radiating scratch-like strise ; the upper and lower 

 surfaces parallel and flat ; composed of vertical cylindrical tubes 

 forming circular cells at the surface 1 line in diameter, and 

 averaging about 2 lines apart ; the intervening space being flat, 

 cellular, and obscurely radiated on the weathered surface by 

 about thirty curved radii : vertical section, tubes irregularly 

 transversely septate by vesicular plates ; spaces between the 

 tubes composed of slightly waved transverse rows of small, 

 curved, vesicular plates, forming a nearly uniform, minutely 

 cellular structure: horizontal section, tubes either plain or 



