青蛤形态学初步观察

青蛤是帘蛤科中分布较广的一种埋栖双壳贝类。壳近圆形，两侧近等，无小月面，有外韧带，主齿三枚，前闭壳肌痕呈半月形，后闭壳肌痕呈椭圆形。肌肉系统由闭壳肌、足伸缩肌、外套膜肌、水管肌、足肌等组成；消化系统分为消化道和消化腺两部分。消化盲囊呈绿色，为主要的消化腺体；鳃是青蛤主要呼吸器官，同时，外套膜也起到辅助呼吸的作用；循环系统为开管式，具后动脉球，血液中含有血清蛋白而使之成为无色液体；排泄系统由肾脏和围心腔腺组成；青蛤是雌雄异体，生殖期间，精巢为乳白至乳黄色，卵巢为粉红色；系统比较简单，具有三对神经节。

A Preliminary Observation on the Morphology of Cyclina sinensis

Cyclina sinensis is a kind of burrowing-type bivalve in Veneridae with wide distribution. The shells, which are circle and symmetry, have external ligament and three cardinal teeth, but no lunula. Anterior adductor scar looks semilunar, while posterior adductor scar ellipsoid. Muscle system includes adductor, pedal retractor muscle, pallial muscle, siphonal muscle, pedal muscle, and so on. Alimentary system consists of two parts: alimentary canal and digestive gland; digestive diverticulum, with the color of green, is the main digestive gland. Gill is the main respiratory organ; mantle also plays the role of assistant respiration. It has open circulatory system with posterior bulbous arteriosus; the blood is colorless because of serum protein. Excretory system is composed of kidney and pericardial gland. It is gouochorism; testis is milky-white to milky-yellow, and ovary is pink. Nervous system is comparatively simple, which has 3 pairs of nervous ganglia.