Some additional Notes on external Features and on the jaw muscles of Orthragoriscus mola (L.)

In 1939 J. M. van Roon and J. J. ter Pelkwijk published some data on two specimens of Orthragoriscus mola (L.) stranded on the Dutch coast. Measurements of bones and muscles of the jaw were given on account of the functional treatise concerning the mechanism of the jaw of Orthragoriscus given by Van Dobben (1935), based upon one specimen that differed in many ways from both individuals we dissected. In the following years, we got three more specimens and an examination of the jaw muscles proved them to be fully agreeing with the two fishes described before. It seems worth while to publish corresponding data and measurements. Specimen C, a female, stranded December 12, 1939 near Kamperduin in the neighbourhood of Schoorl. This fish was more oblong than either of the others. The sides were covered with longitudinal ripples. J. J. ter Pelkwijk dissected it on the beach on December 13. Specimen D, a male caught in a trawl near the coast off Scheveningen December 13, 1940, was brought to the Zoological Garden at The Hague where it was exhibited for a month in a 4 % formol solution. Then it was brought to the Rijksmuseum van Natuurlijke Historie at Leiden, were it was dissected by J. M. van Roon and P. H. Creutzberg. This fish was much smaller than the others and more circular. It had a conspicuous ridge above the eyes and a curved ridge under the eyes and pectoral fins. Specimen E, a female, stranded November 30, 1941 near Schoorl; it was found by Mr. K. Kuiper at Alkmaar, who sent it to the Rijksmuseum van Natuurlijke Historie, where it was dissected by J. M. van Roon and G. P. Baerends on December 11. This fish differed less than C and D from