. Annual report . Fig. 6 Fig. 7 Fig. 8 Fig. 3-8 Eudendrium ramosum Linn. Growth stages (Copy from Allman) The initial part of the sicula is obviously to be considered as the embryosheath, as also suggested by Holm. The hollow nema is, as the writers shale material shows, extendedinto a primary disk []. The complete embryonic shell consists hence of adisk and a short cone, connected by a hollow tube. The question arises,then, whether one of these parts was formed before the other or whether alloriginated together. The answer to this problem is probably furnishedby the development of certain
. Annual report . Fig. 6 Fig. 7 Fig. 8 Fig. 3-8 Eudendrium ramosum Linn. Growth stages (Copy from Allman) The initial part of the sicula is obviously to be considered as the embryosheath, as also suggested by Holm. The hollow nema is, as the writers shale material shows, extendedinto a primary disk []. The complete embryonic shell consists hence of adisk and a short cone, connected by a hollow tube. The question arises,then, whether one of these parts was formed before the other or whether alloriginated together. The answer to this problem is probably furnishedby the development of certain hydroids, that pass through a growth stage 524 NEW YORK STATE MUSEUM which is exactly alike in its structure and which hence can be considered asequivalent to that of the graptolites here under discussion. I copy herefor comparison the successive stages of a tubularian hydroid, Eudendriuraram os um, from Allman [1872, pt2, pi. 13, fig. 12-16]. The similarity ofthe embryos in the graptolites and this hydroid is in
Size: 1175px × 2126px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectscience, bookyear1902
