The annals and magazine of natural history : zoology, botany, and geology . ree from eacli other and from the dor.^al directive septum with itscolmnella-like free end. Exosepta regularly alternate with theentosepta all round the calice, and the ventral directive septum isa little smaller than the other principal septa, thus giving rise to afossula. The stage Iepreseuted is practically that characteristic ofthe fully developed corallum. to the protosepta ; sometimes partial or entire silicification ofthe corallum has taken place, and rendered the preparationof sections practically impossible; w
The annals and magazine of natural history : zoology, botany, and geology . ree from eacli other and from the dor.^al directive septum with itscolmnella-like free end. Exosepta regularly alternate with theentosepta all round the calice, and the ventral directive septum isa little smaller than the other principal septa, thus giving rise to afossula. The stage Iepreseuted is practically that characteristic ofthe fully developed corallum. to the protosepta ; sometimes partial or entire silicification ofthe corallum has taken place, and rendered the preparationof sections practically impossible; while in such as Dancanellahoreahs the original tip is wanting, and when first collectedfour, five, or six pairs of septa are frequently exposed toview (fig. 17). Since the publication of my first paper I have made con-siderable efforts to secure from various sources specimens of 234 Prof. J. E. Duerden on the rugose corals particularly adapted for investigating thisspecial problem. The number now available has enabledme to demonstrate the presence of six primary septa in.
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Keywords: ., bookcentury1800, bookdec, booksubjectnaturalhistory, bookyear1838
