摘要
本文研究的双切尾虫Ditomopyge是一个新种,定名为四川双切尾虫Ditomopyge sichuanensis(sp.nov),标本产自四川南部古宋下二叠统铜矿溪组。该组过去很少发现三叶虫化石,故四川双切尾虫的发现,不仅对铜矿溪组的划分、对比提供了可靠的三叶虫化石依据,而且对研究双切尾虫的地质地理分布,提供了新的化石资料。
The specimens which are described here as Ditomopyge sichuanensis (sp. nov.) were collected by Prof. Chao Zhong-yuan and his students of the Department of Geology, Northwest University from the Early Permian Tongkuangxi Formation in Gusong district, South Sichuan in 1963.The diagnostic features of the new species are as follows:Cephalon semielliptical in outline, a little elongated Glabella pyriform, expanded in front, largest width at the middle line of the frontal glabellar lobe and the width is equal to the distance between the 2p furows, with three pairs of lateral glabellar furrows, the posterior one is long and biforcates adaxially with one of its branches united with each orther to form a transglabellar furrow, anather one curving backward to meet the occipital furrow forming a pair of lateral preoccipital lobes and a subrectangular median preoccipital lobe. Occipital ring narrowed laterally, its anterolateral cornars papillate and its posterior margin are straight. Fixigenae is narrow, about 1/3 width of the narrowest part of glabella. Eyes are reniform, its length equals to the 1/3 glahellar length, being situated behind the middle line of the glabella. Librigenae with Jong genal spines reaching seventh thorax segment.Thorax is incomplete, only seven segments are preserved, the axis is slightly wider than pleurae.Pygidium is subsemielliptical in outline, with a narrow border becoming narrower back-wad. The Axis tapered backward, with 22 axial rings and a terminal. Pleurae is composed of 12 pleural segments, with depressed lateral part, pleural furrows are deep and narrow.This species is similar to Ditomopyge yungchangensis described by Wang (Wang, 1937, pp. 361-364, pl. 1, fig. la-b), but differs from the latter chiefly in the narrower cephalon, the larger eyes, the prominent first and second glabellar furrows, the absence of a median nod on occopital ring, the large numbers of pygidial axial segments, the depressed lateral part of pleural lobes and in the absence of the coarse granules on cephalon and the fine granules on pygidium.
出处
《地质科学》
CAS
CSCD
北大核心
1989年第3期302-304,共3页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
二叠世
三叶虫
四川
Early Permian Trilobites, S. Sichuan Province
