I. On the organization of the fossil plants of the coal-measures. —Part VII. Myelopteris, psaronius, and kaloxylon

Abstract

The existence or non-existence of the remains of Palms in the Carboniferous strata has long been a debated geological question. Accepting the determinations of Corda as announced in his ‘Flora der Vorwelt,’ many geologists admitted these true endogens into their lists of Carboniferous plants. Cotta had figured, in his ‘Dendrolithen,’ three very anomalous stems, under the names of Medullosa porosa , Stellata , and elegans . Corda, in his 'Flora der Vorwelt,’ subsequently figured two stems from Carboniferous strata obviously allied to one, at least, of Cotta’s types, under the names of Palmacites carbonigerus and P. leptoxylon , which he placed in the class of Palms. Cotta’s figures of Medullosa elegans are very misleading, though they are not very unlike the specimens which he probably described. Some specimens now in the British Museum which came direct from Cotta, and for having my attention drawn to which I am indebted to my friend Mr. Carruthers, exhibit a remarkable areolation when cut transversely. This areolation Cotta has not only copied but exaggerated; hence the peculiar aspects of his figures 1 & 8 of his Medullosa elegans ; it certainly is not a constant and normal feature, but the result of some change produced subsequent to the life of the plant—most probably a consequence of partial desiccation of the stem. Cotta’s drawings of the cortical layer also are very misleading; hence it is very unsafe to accept his delineations apart from the study of his specimens, some of which, I fear, are no longer to be found. The consequence is that two of his species, M. stellata and M. porosa , remain too obscure to be relied upon without further evidence than Cotta has handed down to us. The first to throw doubt upon the Monocotyledonous character of these plants was M. Brongniart in his ‘Tableau des genres de Végétaux fossiles,’ published in 1849, extracted from the ‘Dictionnaire Universel d’Histoire Naturelle.’ He identified Cotta’s Medullosa elegans with some important plants not uncommon in the Carboniferous beds of Autun; and whilst he thought that these specimens displayed a structure analogous to that of some Monocotyledons, especially of Draœena, he adds, “il y ait des différences fort essentielles et qui rendent très-difficile d’établir des rapports entre ces fossiles et les végétaux vivants”*. M. Brongniart consequently proposed to make Cotta’s Medullosa elgans the type of a distinct genus under the name of At a later page of his work (p. 97) he further gives a list of fourteen Carboniferous Monocotyledons, in which he includes seven species of Trigonocarpum , his proposed genus Myeloxylon , and the Palmacites carbonigerus and leptoxylon of Corda, at the same time declaring that all these supposed Carboniferous Monocotyledons are “ très-douteuses et imparfaitement connues.” At p. 89 of his work he retains Corda’s genus Palmacites , but remarks respecting the two species from the Carboniferous strata, viz. P. carbonigerus and leptoxylon , that they appear to be distinct from the Palms, and probably also from the group of Monocotyledons, thinking them analogous to the Medullosa elegans of Cotta, adding, in reference to the latter plant, “ qui n’est certainement pas un palmier.”