RELATION TO ONTOGENY AND PHYLOGENY IN ASTEROID, WITH PATICULAR REFERENCE OF THE MOST LIVING PRIMITIVE GENUS, LUIDIA

(1)观察了斑纹夜蛾的变态发育过程。卵的直径为173微米。受精后一个半小时，卵裂完全呈放射状。胚胎通过皱纹囊胚期发育成双羽状幼体。受精后40d，双耳器后部逐渐发生变态。在这一阶段，出现了9根针状体，与成人骨骼的终板相对应。一周后，二回羽毛长达2.5毫米。受精后64天，变态完成，幼体直径约700微米。它们有9只手臂，每只手臂上有2对管脚。(2)本研究表明，本种的个体发育可能在以下几个特征上与鹿亚纲物种的系统发育相关。1.本种的发育与以往报道的本属所有种一致，为非腕足类类型。2.目前的观察结果证实了Mortensen(1938)关于二羽亚纲的形态和系统位置之间的平行关系的观点。这是因为属于第二高级交链孢属群(Doderlein 1920)的现有种的二羽纤毛虫比被归入第三高级Quinaria组的Quinaria的二羽纤毛虫只有一对双羽状纤毛。3.由于变态幼虫和成虫一样只有9只手臂，所以小行星多臂物种的手臂形成时间与鹿纲物种的系统学有关。

(1) In this study, the development of Luidia maculata Muller et Troschel, through metamorphosis was observed. The eggs are 173 mum in diameter. One and half hours after fertilization, cleavage is total and radial. Embryos develop into a bipinnaria through the wrinkled blastula stage. Metamorphosis takes place gradually at the posterior portion of the bipinnaria, 40 days after fertilization. At this stage 9 spicules, corresponding to the terminal plates of adult skeleton, appear. One week later, bipinnariae reach a length of 2.5 mm. Sixty-four days after fertilization, metamorphosis is completed and resulting juveniles are about 700 mum in diameter. They have 9 arms and bear 2 pairs of tube-feet in each arm.(2) This study shows the ontogeny of the present species may be correlated to the phylogenetic relationships of the species of Luidia in the following features. 1.Development of the present species is the non-brachiolarian types as all species of this genus previously reported. 2. The present observations comfirm Mortensen's view (1938) on the parallelism between the form of the bipinnaria, and the systematic position in the genus. Because bipinnaria of the present species belonging to the 2ndly advanced Alternata group (Doderlein 1920) has less one pair of bipinnaria arms than those of L. quinaria, which is included to the 3rdly advanced Quinaria group. 3. Because of just metamorphosed juvenile bearing 9 arms like the adults, the time of arms formation in multiarmed species of asteroid is related to the systematics of Luidia species.