A species of Gyroporella, G. bellerophontis, has recently been described by Rothpletz[325] from Permian rocks in the Southern Tyrol. The thallus is tubular in form and has a diameter of ·5–1 mm.
Dactylopora.
The genus Dactylopora was founded by Lamarck[326] on some fossil specimens from the Calcaire Grossier and included among the Zoophytes. D’Orbigny afterwards included it among the Foraminifera, and the structure of the calcareous body has been described by Carpenter[327] and other writers on the Foraminifera. In a specimen of Dactylopora cylindracea Lam. from the Paris basin, for which I am indebted to Munier-Chalmas, the tubular thallus measures 4 mm. in diameter; at the complete end it is closed and bluntly rounded. The wall of the tube is perforated by numerous canals, and contains oval cavities which were no doubt originally occupied by sporangia. The shape of the specimens is similar to that of Diplopora, but the canals and cavities present a characteristic and more complex appearance, when seen in a transverse section of the wall, than in the older genus Diplopora. Gümbel has given a detailed account of this Tertiary genus in his memoir on Die sogenannten Nulliporen[328]; he distinguishes between Dactyloporella and Gyroporella by the existence of cavities in the calcareous wall of the tube in the former genus, and by their absence in the latter. The oval cavities in a Dactyloporella were originally occupied by sporangia; in Diplopora and Gyroporella the sporangia were probably borne externally and on an uncalcified portion of the thallus.
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In addition to the few examples of fossil species described above there are numerous others of considerable interest, which illustrate the great wealth of form among the Tertiary and other representatives of the Verticillate Siphoneae.
Reference has already been made to Vermiporella as an example of a Silurian genus. Other genera have been described by Stolley from Silurian boulders in the North-German drift under the names Palaeoporella, Dasyporella and Rhabdoporella[329]; the latter genus is compared with the Triassic Diplopora, and the two preceding with the recent Bornetella.
Schlüter has transferred a supposed Devonian Foraminiferal genus, Coelotrochium[330], to the list of Palaeozoic Siphoneae. Munier-Chalmas regards some of the fossils described by Saporta under the name of Goniolina[331], and classed among the inflorescences of pro-angiospermous plants, as examples of Jurassic Siphoneae. The shape and surface-features of some of the examples of Goniolina suggest a comparison with Echinoid spines, but the resemblance which many of the forms in the Sorbonne collection present to large calcareous Siphoneae is still more striking. A comparison of Saporta’s fig. 5, Pl. xxxiii. and fig. 4, Pl. xxxii. in volume iv. of the Flore Jurassique, with the figures given by Solms-Laubach[332] and Cramer[333] of species of Bornetella brings out a close similarity between Goniolina and recent algae; the chief difference being the greater size of the fossil forms. The possibility of confounding Echinoid spines with calcareous Siphoneae is illustrated by Rothpletz[334], who has expressed the opinion that Gümbel’s Haploporella fasciculata is not an alga but the spine of a sea-urchin.
Among Cretaceous forms, in addition to Goniolina, which passes upwards from Jurassic rocks, Triploporella[335] and other genera have been recorded.
Uteria[336] is an interesting type of Tertiary genera; it occurs in the form of barrel-shaped rings, which are probably the detached segments of a form in which the central axial cell was encrusted with carbonate of lime, but the sporangia and the whorls of branches differed from those of Cymopolia in being without a calcareous investment.