论Finospirifer的形态源流

本文叙述腕足动物石燕类Finospirifer(鳍石燕)属的特殊性状在分类中的意义,并试用中槽壳线程式、生成顺序及其它特性分析比较Cyrtospirifer chaoi(赵氏弓石燕)与Finospirifertaotangensis(陶塘鳍石燕)的形态特征,阐述两者在形态演变中的遗传与变异的关系,认为前者可能是后者的直系亲型。

ON THE MORPHOLOGICAL DERIVATION OF GENUS FINOSPIRIFER

Since 1931, Amadeus W. Grabau convinced that the nature, the formality and the appearing order of the sinual costae are the striking characteristcs for taxonomy about his so called "Spirifer (Sinospirifer)". And then he proposed to use his sinual formulae to classify the species and mutations for his subgenus. Here, we adopt A. W. Grabau's viewpoint to trace the morphological derivation of genus Finospirifer. It is quite interesting to note that the sinual formulae of Finospirifer laolancjeusis (type species of Finosirifer) and Cyrtospirifer chaoi are much alike. The basic sinual formulae of both are 2+I+2, 3+I+3, 4+I+4 and etc. Furthermore, after we studied the other characteristcs, the ontogenesis of both and examined the references about their geological ranges, their distributive localities, we have drawn the following pertinent inference: Finospirifer taotangensis is assumed to be the heredity of Cyrtonpirifer chaoi morphologically.