Morphologic and crystallographic study on the skeletal homology of crinoids (Echinodermata)

在这一年里，我进行了两项与这项资助有关的主要研究；1)三种现代菊科动物发育阶段骨骼生长的扫描电镜观察；2)菊科动物跨古生代-中生代边界快速进化的化石证据。在相模湾小次郎湾采集了日本氧蝇标本，对其产卵和受精后的发育情况进行了监测。此外，还观察了另外两种常见的五戊酸期，如前裂和斑斑病。结果包括：1。本文首次在虎芋中检出肛门板。这是寡孔亚目肛门板的首次报道。肛门板在古生代的三个亚类中都有广泛的发现，但在某些节肢动物上的发现表明它的存在不能作为节肢动物的良好特征。所有这三个关节在五戊烷类柄上共享联合关节。本研究资料，结合以往各种关节的五烷类资料，认为五烷类柄中存在联性是关节的一个良好的突触性特征。在囊样期，柱状体的数量可能增加，但在五戊烷样期，柱状体的数量几乎不变，每根柱状体呈纵向生长。此外，关于晚二叠世-早三叠世节肢动物的资料（日本东北部，内华达州）和参考文献资料显示：越过边界，手臂的韧带关节数量突然减少，关节在韧带激活时获得了手臂自切的能力。这种进化上的新颖性一定与Articulata的成功密切相关。

In this year I conducted two major researches in relation to this grant ; 1) SEM observation of the skeletal growth during developmental stages of three species of modern comatulids, 2) Fossil evidence about the presumable rapid evolutionary changes of the subclass Articulata across the Paleozoic-Mesozoic boundary.Specimens of Oxycomanthus japonicus were collected from Koajiro Cove of Sagami Bay, and their spawning and development after fertilization were monitored. Also, pentacrinoid stage of two other comatulids, Antedon bifida and Decametra tigrina, were observed. The results include :1. Anal plate was detected in pentacrioids of Oxycomanthus j. for the first time. This is the first report of anal plate from the suborder Oligophreatina. The anal plate were widely observed in the three subclasses of the Paleozoic, but this discovery from some articulata implies that its existence cannot be a good character of the articulata.2. All three comatulids share synarthrial articulation in the pentacrinoid stalk. The present data, combined with previous data about pentacrinoids of various articulates, suggest that existence of synarthry in the pentacrinoid stalk would be a good synapomorphic character of the Articulata.3. The number of columnals probably increases during the cystoid stage, but it is almost constant and longitudinal grow of each columnals are observed during the pentacrinoid stage.Also data about Late Permian-Early Triassic articulates, both specimens (NE Japan, Nevada) and data from reference papers, shows the following :4. Across the boundary, the number of ligamentary articulations in the arms suddenly decreased, and articulates have acquired the ability of arm autotomy at ligamentary acticulations. This evolutionary novelty must deeply be related to the suceess of the Articulata.