The Gametophyte of Cardiocarpus Spinatus Graham

Among the more interesting fossils that we have encountered in coal balls from West Mineral, Kansas (Andrews, 1951), is a seed, presumably of cordaitean affinities, with a rather well-preserved gametophyte. It seems to be referable to Cardiocarpus spinatus Graham (1935, p. 165), although it presents much additional information relative to the structure of the integument and gametophyte. The final selection of a name for the seed presented a considerable problem, and because of some general principles of seed nomenclature, it seems desirable to discuss in detail certain historical aspects of the case. In 1828 Brongniart recorded (Prodrome, p. 87) the genus and listed five species. The only description given is as follows: Fruits comprimes, lenticulaires, cordiformes ou reniformes, termines par une pointe peu aigue. Brongniart did not deal with the genus in his monumental 'Histoire des Vegetaux Fossiles' (1828-1838) and seems to have had little or nothing to do with it until 1881 when his work on the silicified seeds appeared. Various other authors, however, have described species of Cardiocarpon, some soon after 1828, and the variation in form illustrated composes a rather incredible array of what are apparently many generic entities. A few examples will suffice to reveal the lack of recognition of any clearly defined generic boundary. Mantell (1844, p. 153, fig. 34-1) figures under the name acutum a round strongly winged seed; the wing apparently entirely encloses the body of the seed. Lindley and Hutton (1831-37, pl. 76) illustrate wingless seed casts under the same name. Dawson (1878, fig. 194b) pictures a seed with a strongly attenuate apex under the same binomial; and Williamson (1877, pl. 15, fig. 122) figures a bicornute seed under the name Cardiocarpon acutum of Lindley and Hutton, although the binomial was originally Brongniart's (1828, p. 87). In 1853 Newberry described samaraeforme as a nearly round seed with two large and distinct wings; while Dawson's figures show cornutum as an elongate winged seed with cornute apex. The above is a very brief introduction into the almost endless range of form of the seeds gathered together under this generic designation. More fuel was added to the flame of confusion when in 1862 Geinitz created the genus Cordaicarpon, the generic description differing in no significant way from that of Brongniart's for Cardiocarpon. Geinitz (1855) described Carpolithes cordai (which he believed to be the seed of Cordaites principalis (Germar) Geinitz) and designated it (in 1862) as the type species of his new genus. In referring to his illustrations (Geinitz, 1855, pl. 21, figs. 7-16), we find it impossible to recognize any characters which set his genus apart from Brongniart's or in any way justify a distinct genus. To further confound later workers these generic names, originally given as