. Bulletin - United States National Museum. Science. DENDROID GRAPTOLITES OP HAMILTON, ONTARIO. 29 As the connecting filaments are very fine, owing to imperfect preservation, they are not always distinct over the whole surface of the frond. Tliis si)ecies is easily distinguished from D. gracilis—even in fragments—by the branches being exceedingly fine (about one-hundredth of an inch in width), with scarcely that distance between them, and witli no approach to the dendritic form of that species. The frond maintains its character even in the young state. The larg- est frond is three and one-half
. Bulletin - United States National Museum. Science. DENDROID GRAPTOLITES OP HAMILTON, ONTARIO. 29 As the connecting filaments are very fine, owing to imperfect preservation, they are not always distinct over the whole surface of the frond. Tliis si)ecies is easily distinguished from D. gracilis—even in fragments—by the branches being exceedingly fine (about one-hundredth of an inch in width), with scarcely that distance between them, and witli no approach to the dendritic form of that species. The frond maintains its character even in the young state. The larg- est frond is three and one-half inches in diameter. It occurs in the Niagara limestone [dolomltic limestones of the cherty beds and in the underlying more shaly rocks; 1884] at Hamilton, Ontario. The speci- men described was obtained by Lieuteuant-Colonel Grant, and presented to the writer. Spencer's description of 1884 adds, that the dissepiments are very delicate, and the margin entire. He further says: This species is easily distinguished from D. gracile [ = D. crassihasale Gurley] by the branches being much finer, less diverging, and with more bifurcations, by the transverse bars being more closely arranged, and by the frond being. Figs. 32, 33.—Dictyonema tenellum Spencer. 32, A small example peeserving the BASAL PORTION. (BY R. S. BASSLER.) 33, A LARGER RHABDOSOME. regularly circulai-, with no general bush-lilce form like that seen in most specimens of D. gracile [crassibasalc]. The largest frond is 9 cm. in diameter. Gurley's descrij^tion of the species is as follows: Polypary cyathiform, in the flattened state radiating from a center; proximal extremity only indistinctly visible in one specimen (text fig. 32). appearing to consist of some kind of a bulbous or fibrous root. Branches straight, mostly mm. wide; a few as narrow as ; occasionally one as wide as and none wider than mm. Number of branches transversely in 25 mm., proxi- mally about 45, distally 50-55. Interspaces conse
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