Shell from Transformations of the Carditidae

心科(软体动物：双壳动物)的生活方式可以是附着型(或上层洞穴)，在这种情况下，它们有发育良好的附属线，或者是自由生活的内部型，在这种类型中，它们有非常弱的附属物，或者一生中完全没有附属物。具有次等边壳层的旋毛虫种类属于前者，而极不等边的Cardita种则属于后者，后者的喙呈原形。对心脏科的解剖学和生态学研究表明，附着性的生活方式比自由生活的生活方式更高级(Yonge，1969)。笛卡尔变换是由嵌入在直角坐标系中的From的简单变形。如果将笛卡尔坐标系内的圆环心虫图转移到一个系统中，在y方向上压缩后，其中对于原始图的y替换Y=9Y/10，作为非常接近的近似的图是…获得了更多关于斯普卡贝壳形态的信息。大头锦鸡儿的壳是背腹压缩的，壳高的降低对应于Y=8y/10。笛卡尔变换似乎适用于比较一个属或一个亚科的近缘属的相关形式。“单剪”是用斜轴X和Y来描述的一种变形。Y轴与y轴成一定角度。如果将直角坐标系统中的腹毛藻的绘制转移到这样的系统中，即对于X=x+y^。Tan345，ﾟ和Y=y，得到了与Megacardita和Cardites物种的壳层形状非常接近的图解。如果将笛卡尔坐标系内的原始图形转换为笛卡尔变形和“简单剪切”的组合系统，就可以得到一个非常接近Megacardita turgida的图形。简单剪切变形和笛卡尔变形与“简单剪切”的结合可能适用于不同亚科物种的壳型比较。壳的形式是如此的奇特，以至于在壳的变换方面不能得到接近的近似。壳型转化的结果表明，囊甲亚科是心脏科中最特化的类群。这也得到了古生物学证据的支持，即Thecaliinae物种仅被认为是活着的形式。较少

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