Functional morphology with particular reference to hinge and ligament in Spondylus and Plicatula and a discussion of relations within the superfamily Pectinacea (Mollusca: Bivalvia).
Functional morphology with particular reference to hinge and ligament in Spondylus and Plicatula and a discussion of relations within the superfamily Pectinacea (Mollusca: Bivalvia).
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功能形态，特别是脊椎属和褶皱属的铰链和韧带，以及果壳总科（软体动物：双壳纲）内关系的讨论。
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发表时间：
1973
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通讯作者：
C. M. Younge
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作者：
C. M. Younge
除了等肌科Dimyidae，果胶类包括Propeamussidae，Pectinidae，Spondylidae和Plicatulidae。目前的调查主要涉及最后两个物种，这两个物种都是由右瓣膜胶结的，具有次级齿和承窝，在瓣膜之间形成球窝接头。这两个以前都没有在生活中进行过检查，也没有对铰链和韧带进行过严格的研究。与果胶科的条件相比，褶皱纲的栉孔板更简单（像Propeamussium的栉孔板一样），但这里和Spondylus的纤毛模式（B（1a）型）更原始。海枣螺与海枣科相似之处在于它有精致的树唇和盖眼;褶螺（和Propeamussium）两者都没有，并且内部的套膜（软膜）是减少的（尽管在Propeamussium中扩大）。在褶形目和脊椎目中，脚已经消失，只与清洁有关;果胶科展示了一系列的足的形式和功能-从运动到深渊附着和清洁。内收肌中“快速”与“捕捉”肌的比例与习性有关，在需要快速内收的地方最大，主要与清洁有关，这在水平放置的双壳类中是一个特别紧迫的问题。在永久附着的物种和游泳的物种中，Pallial眼睛发育良好，当瓣膜张开时，Pallial组织广泛暴露，Pallial眼睛很可能与捕食性攻击的即时反应有关。脊椎动物和褶皱动物的韧带与果胶科（和Propeamussidae）的韧带有惊人的不同。在后两层中发现的长的前、后外韧带层将位于浓缩圆形内韧带层两端的瓣膜连接在一起，在脊椎动物中被融合的角质层所取代。外韧带层向内迁移，在未改变的内韧带层的两侧分开后，在其上方和下方结合（地形学上），形成形态上由前部和后部外韧带层相等组成的左侧和右侧区域。形成初级韧带次级延伸的融合的角质层周沟的向内延伸，很可能与铰板（以及牙齿和牙槽）的性质改变有关，铰板的性质改变为交叉层状文石，而不是Pectinidae中存在的片状方解石。结合的内外韧带层产生了更强大的韧带，以满足更大的瓣的需要;次级角质膜延伸仅用于连接瓣，通过次级齿和窝保持对齐。铰链和韧带明显的双侧不对称是骨水泥形成的结果;骨水泥形成的梳状骨和Hinnites也存在类似的情况。在褶皱中差异更大。地幔边缘的向内生长导致在现在的亚边缘韧带之上的结合。这是非常压缩的横向平面成为箍状的右肢越长。其基部断裂，但两半保持接触，功能不受影响。与脊柱一样，前韧带层和后韧带层的一半在内韧带层的两侧结合。由于铰链板的背侧过度生长，分泌外韧带层的上皮细胞形成腔室的两侧和顶部，腔室的基部是外套峡（形成内韧带层）。与瓣膜的接触仅通过外韧带层进行。骨膜在背侧中线融合，与韧带分离无关。由于内韧带层分为左右两半，瓣的结合是通过次级齿有效的，这里的次级齿比脊椎动物的背侧齿更长，但与脊椎动物一样，由交叉的片状文石组成。这四个科的进化始于古生代种群，伴随着地幔腔中器官的变化--栉齿、唇、盖层眼等--沿着沿着不同于韧带变化的路线进行。前者特别涉及原始Propeamussidae，主要局限于深水，和普遍分布的Pectinidae，后者Spondylidae和Plicatulidae。足的变化与最终的习性有关，在前足科中，这种习性是不变的自由;在栉足科中，这种习性是不变的附着、自由或粘结;在脊椎动物科和褶足动物科中，这种习性是不变的粘结，在后者中，这种习性发生得较早，并涉及到足的丧失。脊椎虫科与栉虫科的分离，随着韧带结构的完全不同而得到更充分的证实;褶虫科的差异是如此深刻，以至于提出了将其提升到超科地位的问题。
Excluding the isomyarian family Dimyidae, the Pectinacea comprise the families Propeamussidae, Pectinidae, Spondylidae and Plicatulidae. Present investigations are primarily concerned with species of the last two, both of which are cemented by the right valve, with secondary teeth and sockets which form ball and socket joints between the valves. Neither has previously been examined in life or the hinge and ligament critically studied. Comparing throughout with conditions in the Pectinidae, the ctenidia in Plicatula are simpler (like those of Propeamussium ) but both here and in Spondylus the ciliary pattern (type B (1a)) is more primitive. Spondylus resembles the Pectinidae in that it has elaborate arborescent lips and pallial eyes; Plicatula (and Propeamussium ) has neither, and the inner mantle folds (velum) are reduced (though enlarged in Propeamussium ). The foot is lost in Plicatula and in Spondylus has solely to do with cleansing; the Pectinidae display a range of pedal form and function - from locomotion to byssal attachment and to cleansing. The ratio of ‘quick’ to ‘catch’ muscle in the adductor is associated with habit, being greatest where need for rapid adduction is greatest, primarily in connexion with cleansing, a matter of particular urgency in horizontally disposed bivalves. Pallial eyes - as well developed in permanently attached as in swimming species - are most probably concerned with immediate response to predatory attack on pallial tissues widely exposed when the valves gape. The ligament in both Spondylus and Plicatula is surprisingly different from that in the Pectinidae (and Propeamussidae). The long anterior and posterior outer ligament layers found in the two last which unite the valves at either end of the condensed rounded inner ligament layer are replaced in Spondylus by fused periostracum . The outer ligament layers have migrated inwards and, after dividing on either side of the unchanged inner ligament layer, unite (topographically) above and below it, forming morphologically left and right areas composed equally of anterior and posterior outer ligament layers. The inward extensions of the fused periostracal grooves which form the secondary extensions to the primary ligament may well be associated with the change in nature of the hinge plate (and thus of teeth and sockets) to crossed-lamellar aragonite instead of the foliated calcite present in the Pectinidae. The combined inner and outer ligament layers produce the more powerful ligament demanded by the more massive valves; the secondary periostracal extensions serve only to unite the valves which are maintained in alinement by way of the secondary teeth and sockets. The conspicuous bilateral asymmetry in the hinge and ligament is a result of cementation; similar conditions exist in the cemented pectinid, Hinnites . In Plicatula differences are much greater. Inward growth of the mantle margins results in union above the now submarginal ligament. This is extremely compressed in the transverse plane becoming hoop-like with the right limb the longer. Basally it fractures, although the two halves remain in contact and function is unaffected. As in Spondylus, the halves of the anterior and posterior ligament layers unite on the two sides of the inner ligament layer. Owing to dorsal overgrowth by the hinge plate, the epithelia secreting the outer ligament layers form the two sides and roof of a chamber the base of which is the mantle isthmus (forming the inner ligament layer). Contact with the valves is exclusively by way of the outer ligament layers. The periostracum fuses in the mid-line dorsally and does not contribute to the ligament from which it is separated. Owing to the division of the inner ligament layer into right and left halves, union of the valves is effectively by way of the secondary teeth, here more dorsally extended than in Spondylus but, as there, composed of crossed-lamellar aragonite. Evolution of these four families starts in Palaeozoic stocks with modifications of organs in the mantle cavity - ctenidia, lips, pallial eyes, etc. - proceeding along lines distinct from those involving modifications in the ligament. The former particularly concern the primitive Propeamussidae, largely confined to deep water, and the universally distributed Pectinidae, the latter the Spondylidae and the Plicatulidae. Modifications of the foot have to do with final habit which is invariable freedom in the Propeamussidae, byssal attachment, freedom or cementation in the Pectinidae, and invariable cementation in the Spondylidae and Plicatulidae, the process occurring earlier in the latter and involving loss of the foot. Separation of the Spondylidae from the Pectinidae is more fully established with the present demonstration of the totally different ligamental structure; the difference is so profound in the Plicatulidae as to raise the question of elevating this to superfamily status.