On the structure and affinities of the genus Monticulipora and its sub-genera, with critical descriptions of illustrative species . that any descriptionsof the minute structure of this genus, taken from authentic Americanexamples, have as yet been made public, either by the distinguished APPENDIX. 233 author of the genus or by any other observer. Judging from the de-scriptions and figures which Dybowski has given of the forms which hehas included under the name of Trcmatopora, Hall, it seems safe, how-ever, to conclude that we have to deal here with a peculiar type ofMonticuliporoids, which di
On the structure and affinities of the genus Monticulipora and its sub-genera, with critical descriptions of illustrative species . that any descriptionsof the minute structure of this genus, taken from authentic Americanexamples, have as yet been made public, either by the distinguished APPENDIX. 233 author of the genus or by any other observer. Judging from the de-scriptions and figures which Dybowski has given of the forms which hehas included under the name of Trcmatopora, Hall, it seems safe, how-ever, to conclude that we have to deal here with a peculiar type ofMonticuliporoids, which differ in important respects from all the formswhich have been described in the preceding portion of this the brief diagnosis above given, and the accompanying engrav-ing (fig. 48), it will be seen that these types possess a dimorphic coral-lum, composed of large and small corallites, which differ both in sizeand in their internal structure, while a third series of corallites is repre-sented by an abundance of spiniform corallites. The large coral-lites are oval, with thick lamellar walls (fig. 48, a), and with a very. Fig. 48.—A, Tangential s&ci\onoi Trcmatofora colltculata, Eichw. (Dyb.), enlarged, showingthe large tubes surrounded by small angular corallites, and having spiniform corallites developed close beside them ; B, Outer portion of a transverse section of the same, wherethe tubes are cut longitudinally, enlarged, showing the large corallites, with their few andremote tabula, and the closely tabulate interstitial corallites. From the Lower Silurianof Russia. (Copied from Dybowski.) small number of complete horizontal tabular (fig. 48, b). The smallcorallites are numerous, angular in shape, with imperfect walls, andwith very numerous, close-set, horizontal tabulae (fig. 48, c), which maybecome more or less vesicular. On the lateral margins of each of thelarge corallites are also developed two or three conspicuous spiniformcorallites. The interstitial corallit
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