At hatching Scophthalmus maximus shows no cartilaginous and no bony structure. Meckel's cartilages appear when the fry are 1 day old, followed on day 2, by formation of the trabecular bars, fused at the outset to form a trabecula communis. Concurrently, the palatoquadrates complete the mandibular arch, and the first two pairs of ceratobranchials, associated with a pair of hyoid bars, form the beginnings of the hyobranchial system. By day 3, the parachordals have fused with the trabecular bars, the hyosymplectics have linked to the hyoid bars by interhyals, and the first four pairs of ceratobranchials have appeared. The first bony structures appear: the preoperculars. On day 8, the frontals develop above the orbits and the maxillaries and dentaries appear. On day 10, the primordia of the taeniae marginales appear, the palatoquadrates bear a pterygoid process, and to the branchial basket have been added the fifth pair of ceratobranchials and the four pairs of epibranchials. On day 12, both pairs of posterior pharyngobranchials are present. The premaxillaries develop in front of the maxillaires, and retroarticulars and the angulars complete the lower jaws. On day 13, a thin parasphenoid contributes to the floor of the neurocranium, and ectopterygoids and entopterygoids to the splanchnocranium. The set of opercular bones is complete. On day 15, the tectum synoticum closes the braincase posteriorly. The splanchnocranium possesses a basihyal and the pharyngobranchials of the first epibranchials. On day 18, the tectum posterius completes the dome of the braincase. The rear end and lateral walls of the skull are formed by the basioccipital, the exoccipitals, the pterotics, and the parietals. The suspensorium is nearly complete. From day 10, the first resorptions begin in parallel with the construction of the chondrocranium. Meckel's cartilages each split in two, then the posterior part of the trabecular bars disappears. On day 23, the right taenia marginalis separates from the lamina orbitonasalis and curves towards the centre. Simultaneously, the right eye begins its migration to the left. This is the only metamorphosis-linked asymmetry to appear during the development of the chondrocranium. On day 25, many more bony structures appear, a characteristic of this stage: the nasals, lateral ethmoids, mesethmoid, sphenotics, prootics, pleurosphenoids, epiotics, and supraoccipital. From this stage on, the bony structures continue to develop, while the front of the neurocranium and the jaws undergo a deep remodelling due to metamorphosis. The left taenia marginalis does not appear reduced until day 29. By day 45, there remain only a few small elements of the cartilaginous skull. 1998 The Fisheries Society of the British Isles

The postembryonic development of the bony cephalic skeleton in the common sole Solea solea, observed from hatching to the juvenile stage or postmetamorphic larva, appears to follow a similar chronological order to that observed in other Pleuronectiformes and Perciformes and the sequence in bone formation is a response to functional demands. At hatching, S. solea has no bony structure. On day 4, only the outlines of maxillaries and opercular bones are visible. On day 6, a thin parasphenoid appears between the orbits and isolates the braincase from the buccal cavity making food ingestion possible without any impact on the brain. On day 8, the dentaries form and two small preopercular bones appear on each side of the head. On day 9, at weaning from the yolk sac, branchial arches support the gill filaments (used for respiration and trapping phytoplankton which pass through the open mouth). On day 10, the premaxillaries develop in front of the maxillaries. The superimposing of the maxillaries and the premaxillaries is a typical feature of species possessing an acanthopterygian protractile mouth at the adult stage. On day 12, the frontals develop above the orbits and the set of opercular bones is complete. On day 18, the migration of the left eye begins. On day 20, the left eye has moved to the median crest of the head. On day 23, both eyes are located on the same side. On day 26, the braincase is formed by a basioccipital, exoccipitals, pterotics, sphenotics and a supraoccipital. On day 50, new structures have appeared, others have developed and have undergone an extensive remodeling due to metamorphosis. 2001 The Fisheries Society of the British Isles

No abstract

The aim of this study is to describe the drinking mechanism in two iguanid species, Anolis carolinensis and Oplurus cuvieri. Both live in varied ecological environments where water may be either very abundant or exceedingly scarce. Anolis carolinensis is an arboreal species of the southern United States; in its environment, water is constantly available in drops or small reservoirs. Oplurus cuvieri lives in northwestern Madagascar, enduring very dry and very wet seasons and high insolation. In the dry season, few pools of water or dewdrops remain available. Light and X-ray filming of drinking revealed that the two species almost always use similar mechanisms to introduce water into the buccal cavity. During immersion, the tongue is used to collect water and push it from the front to the back of the buccal cavity. During emersion, water reaches the esophagus, mainly as a result of gravity. In A. carolinensis, this mechanism is used regardless of the amount of water available. In O. cuvieri, the role of the tongue is less important when water is abundant. In similar conditions, therefore, the two species of Iguania use similar mechanisms for collecting and swallowing water. This drinking mechanism has been observed in Lacerta viridis in the sister-group Scleroglossa.

The structure of the bony tubercles of the turbot, Scophthalmus maximus (L., 1758), was examined using ground sections, microradiography, SEM, and TEM. The tubercles are small, isolated, mineralized conical plates randomly distributed in the eyed side of the body. They are composed of three layers: the outer limiting layer, the external layer, and the basal plate, which make up the thin and flat elasmoid scales of Teleostei. The main difference between regular elasmoid scales and bony tubercles lies in the organization and the growth of the basal plate. Indeed, the conical shape of the tubercle is the result of a prominent thickening of the central part of the basal plate where the collagen matrix is organized in a complicated three-dimensional network. Densely packed thick collagen fibrils form superimposed plies organized in a plywood-like structure that resembles that of the elasmoid scales but it is criss-crossed by numerous vertical sheets of thin collagen fibrils. The tubercles originate from thin and flat plates located in the skin of larvae and juveniles, whose structure is that of regular-developing elasmoid scales. Thus, the tubercles of Scophthalmus maximus could be considered as modified elasmoid scales rather than bony structures. They might be the result of specific arrangements related to the general trend of reduction of the dermal skeleton in the teleostean lineage.