12.—Further Observations on some Lower Carboniferous Seeds and Cupules

J. G. Long
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引用次数: 47

Abstract

Synopsis Twenty-eight specimens of the seed genus Dolichosperma have been examined. Fourteen are assigned to D. sexangulatum Long; these possess six or seven integumental lobes which extend apically as free tentacles equal in length to the seed body except when damaged or broken off. Fourteen other specimens are named D. pentagonum sp. nov. These are smaller and usually have five integumental lobes (less commonly six or seven). Long apical tentacles have not been seen in this species. Evidence is adduced that Anasperma burnense Long is the mature prothallial seed developed from the ovule Eurystoma trigona Long. Eurystoma angulare Long sometimes possesses five integumental lobes and the free apical lobes vary in length. Compressed megaspores macerated from cupules of Stamnostoma huttonense Long sometimes have three abortive spores in a compact group at the apex. Ovules of Eccroustosperma langtonense Long were borne in small bunches (probably pendent) on short pedicels; one specimen of this seed shows three well-developed separate abortive spores around the apex of the functional megaspore. The cupule of Calathospermum fimbriatum Barnard shows a structure suggesting that it may have evolved from a pair of cupules. Twelve to fourteen ovules were sometimes formed in the entire cupule though most of these were probably abortive. Some possible seed embryos are described and discussed, and an outline classification of seeds in the order Lagenostomales is proposed.
12.——对一些下石炭世种子和小丘的进一步观察
研究了28个种子属的标本。14个分配给d.s sexangulatum Long;它们具有六或七个被皮裂片,顶端延伸为与种体等长的自由触手,除非被损坏或折断。其他14个标本被命名为D. pentagonum sp. nov.这些较小,通常有五个被盖裂片(较少的是六个或七个)。在这个物种中没有看到顶端的长触须。有证据表明,赤弯草是由三角草(Eurystoma trigona Long)胚珠发育而成的成熟原生种子。角状Eurystoma:长,有时有5个被裂片,自由的顶端裂片长度不等。从huttonense长雄蕊的小梗浸渍的压缩大孢子有时在先端有三个败育孢子在一个紧密的组。长胚珠生于小束(可能悬垂)在短花梗上;这个种子的一个标本显示在功能大孢子的顶端周围有三个发育良好的分离的败育孢子。巴纳德所发现的这对羽衣甘蓝的结构表明,它可能是从一对羽衣甘蓝进化而来的。有时在整个对中形成12至14个胚珠,尽管其中大多数可能是流产的。对几种可能存在的种子胚进行了描述和讨论,并提出了一种lagenostomale目种子的大致分类。
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