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| Keywords: The Quarterly journal of the Geological Society of London (12711770344).jpg 44 <br> PROCEEDINGS OF THE GEOLOGICAL SOCIETY <br> to have been figured or described; but Goldfuss and D'Orbigny <br> have figured a mould of its interior and I obtained a similar prepa- <br> ration fig 7 by removing the upper valve from one of Mr Pratt's <br> specimens with a hammer and chisel <br> Figs 6 7 ” Upper valve ofH Toucasianus <br> Fig 7 <br> Fig 6 Exterior of the upper valve ; \ <br> Fig 7 Mould of the interior of upper valve ; f I m n duplicatures ; x fracture <br> showing canals ; c cartilage ; u left umbo ; ” the arrows indicate the <br> supposed direction of the branchial currents <br> This mould shows the umbo turned forwards and having a deep <br> furrow on each side caused by processes from the upper valve On <br> the dorsal side of the umbo close to the ligamental inflection is a <br> small conical elevation omitted in the figures of Goldfuss and <br> D'Orbigny representing the cartilage or one of its divisions <br> A plaster-cast taken from this mould gives the form of the interior <br> to a certain extent ; that is to say it shows the umbonal cavity the <br> cartilage-pit a deep furrow winding round the adductor and siphonal <br> inflections and the bases of the hinge-teeth <br> With the help of this mould I filled up the umbonal cavity of the <br> other specimen the lower valve of radiosus and then took from <br> it a plaster- cast fig 5 which gives what I believe to have been the <br> form of the upper valve with its processes complete <br> To test the correctness of this model I made a number of sections <br> both transverse and longitudinal of Hippurites in which both valves <br> were preserved These show that the two prominent hinge-teeth <br> were extensively under-cut by the umbonal cavity fig 8 u so as <br> to appear suspended by thin plates Each tooth supports a process <br> corresponding in shape to the muscular impressions in the lower <br> valve ; the anterior projecting horizontally ; the posterior vertical <br> and tooth-like longer indeed than the tooth to which it is attached ; <br> but thinner than in the model not nearly filling the cavity for its re- <br> ception fig 3 «' Both these muscular apophyses are under-cut so <br> as not to interfere with the channel which winds round the inflections <br> This explanation of the hinge-teeth and muscular processes has 35614604 110213 51125 Page 44 Text v 11 http //www biodiversitylibrary org/page/35614604 1855 Geological Society of London NameFound Hippurites NameConfirmed Hippurites EOLID 4773611 NameBankID 4195877 NameFound Toucasianus Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 11 1855 Geology Periodicals Smithsonian Libraries bhl page 35614604 dc identifier http //biodiversitylibrary org/page/35614604 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-23 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12711770344 2015-08-26 20 58 07 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1855 Photos uploaded from Flickr by Fæ using a script | ||||
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