Memoirs of the Geological Survey of India. Palaeontologia Indica Being Figures and Descriptions of the Organic Remains Procured During the Progress of the Geological Survey of India

The ligament area is shorter in the right valve than in the left with the ligament pit so shallow that the difference of level as compared with the margins is scarcely perceptible. [...] To them6 THE MOLLUSCA OF THE RANIKOT SERIES is due the finely radiate structure of the substance of the right valve which becomes noticeable in certain forms of weathering. [...] The occurrence at a few miles' interval and at exactly the same geolgical horizon of the normal specimens of Mazar Drik and the aberrant form of the Des valley disposes of all possibility of splitting up the species either on zoological or on stratigraphical grounds. [...] the only one showing any approach to the development of the pallial markings characterising O. acutirostris are certain species of the group of O. elegans ; but besides many conspicuous differences in the characters of the shell such as the exogyroid umbo of the elegans group a conspicuous distinction rsides in the fact that the pallial markings become wider-spaced as they recede"THE MOLLUSC [...] The other specimens agree better with the Laki and Khirthar forms of O. multicostata as regards the closeness of the ribbing.