The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . on thence arisingis much to be regretted. In the Testicardines, of which the genusTerebratula may be taken as an example, five or six pairs of musclesare stated by A. Hancock, Gratiolet and others to be connectedwith the opening and closing of the valves, or with their attachmentto or movements upon the peduncle. First of all, the adductorsor occlusors consist of two muscles, which, bifurcating near thecentre of the shell cavity, produce a large quadruple impressionon the internal surface of the sm
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . on thence arisingis much to be regretted. In the Testicardines, of which the genusTerebratula may be taken as an example, five or six pairs of musclesare stated by A. Hancock, Gratiolet and others to be connectedwith the opening and closing of the valves, or with their attachmentto or movements upon the peduncle. First of all, the adductorsor occlusors consist of two muscles, which, bifurcating near thecentre of the shell cavity, produce a large quadruple impressionon the internal surface of the small valve (fig. 13, a, a), and a singledivided one towards the centre of the large or ventral valve (fig. 12,a). The function of this pair of muscles is the closing of the other pairs have been termed divq,ricators by Hancock, orcardinal muscles ( muscles diducteurs of Gratiolet), and havefor function the opening of the valves. The divaricators proper arestated by Hancock to arise from the ventral valve, one on eachside, a little in advance of and close to the adductors, and after. rapidly diminishing in size become attached to the cardinal process,a space or prominence between the sockets in the dorsal accessory divaricators are, according to the same authority, apair of small muscles which have their ends attached to the ventralvalve, one on each side of the median line, a little behind the unitedbasis of the adductors, and again to the extreme point of the cardinalprocess. Two pairs of muscles, apparently connected with thepeduncle and its limited movements, have been minutely describedby Hancock as having one of their extremities attached to this dorsal adjustors are fixed to the ventral surface of the peduncle,and are again inserted into the hinge-plate in the smaller ventr(d adjustors are considered to pass from the inner extremity
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
