Shell from Transformations of the Carditidae

心足科（软体动物：双壳纲）的生活方式可能是由足部附着的上足部型（或上层穴居者），在这种情况下，它们有发育良好的足部线，或者是自由生活的动物型，它们有非常弱的足部或一生完全没有足部。具有近等边壳的环状鸟属前者，具有孕喙的强不等边环状鸟属后者。对心脏科的解剖学和生态学研究表明，依附于身体的生活方式比自由生活的生活方式更高级（Yonge, 1969）。笛卡尔变换是一种简单的变形，它是由一个直角坐标系所组成的。如果将笛卡尔坐标系下的室性心动图转换为y向压缩后的系统，将原图的y代入y = 9y/10，得到了非常非常接近的图，得到了C. spurca的壳形。C. turgida具有背腹侧压缩壳，壳高度减小对应于Y = 8y/10。笛卡尔变换似乎适用于比较属中的相关形式或亚科中密切相关的属。“简单剪切”是用斜轴X和Y来描述的变形。Y轴与Y轴呈斜角rheta。如果将在笛卡尔坐标系中绘制的C.脑室图转换为X= X +y^。tan345 ^和Y= Y，得到了一个非常接近Megacardita和Cardites类的壳形图。如果将笛卡尔坐标系内的原始图转换为笛卡尔变形和“简单剪切”的组合系统，则可以得到非常接近于Megacardita turgida的图。简单剪切变形和笛卡尔变形与“简单剪切”的组合可以适用于比较不同亚科物种的壳形式。在腹缘有一个血腔。壳层形式是如此奇特，以至于不能用壳层的变换得到近似的形式。壳形转化的结果表明，藻科是藻科中最特化的类群。这也得到了古生物学证据的支持，这些证据表明，珊瑚科物种只被认为是有生命的形式。少

The mode of life of Carditidae (Mollusca : Bivalvia) may be either of the byssally attached epifaunal type (or upper tier burrower), in which case they have well-developed byssal threads, or of the free-living infaunal type, in which they have a very weak byssuses or completely lack them throughout all their life. Cyclocardia species with a subequilateral shell belong to the former and strongly inequilateral Cardita species with a prosogyrate beak to the latter. Anatomical and ecological studies of the Carditidae suggest that the byssally attached mode of life is more advanced than the free-living type (Yonge, 1969).Cartesian transformations are a simple deformation of from inscribed in a system of rectangular co-ordinates. If a drawing of Cyclocardia ventricosa within a system of Cartesian coordinates is transferred to a system, after compression in the y-direction, in which for the y of the original diagram substituting Y = 9y/10, a drawing which is a very is a very close approximati … More on to the shell form of C. spurca is obtained. C. turgida has a dorso-ventrally compressed shell, which is subject to a reduction of shell height corresponding to Y = 8y/10. Cartesian transformations seem to be applicable to compare related forms in a genus or in closely related genera of a subfamily.The "simple shear" is a deformation described in terms of the oblique axes X and Y. The Y axis is inclined to y axis at an angle rheta. If the drawing of C. ventricosa within a system of Cartesian co-ordinates is transferred to a system in which for the X=x+y^. tan 345^ﾟ and Y=y, a drawing which is a very close approximation to the shell form of Megacardita and Cardites species is obtained. If the original drawing within a system of Cartesian co-ordinates is transferred to a system of combination of the Cartesian deformation and the "simple shear", a drawing which is a very close aproximation to Megacardita turgida is obtained. The simple shear deformation and the combination of the Cartesian deformation and the "simple shear" may be applicable to compare shell forms of species belong to different subfamilies.The Thecaliinae species have a blood chamber at the ventral margin. The shell form is so peculiar that a close approximation is not obtained in terms of transformations of shell from. The result of shell form transformation suggests that the Thecaliinae is most specialized group within the Carditidae. This is also supported by the paleontological evidence that the Thecaliinae species are only known as living forms. Less