A new species of Unio

Shell oblong, attenuated towards the anterior part, inaequilateral, rather inflated, very thin, rather smooth but covered with a thin closely wrinkled epidermis, greenisholive, with two indistinct green rays on the posterior slope. Upper- or hinge-margin nearly straight, lower margin irregularly curved, its anterior part rising obliquely into the anterior margin, which is regularly rounded and meets the upper margin at an obtuse angle. Posterior side gradually sloping to a wedgelike point. Beaks slightly incurved, eroded, placed at the distance of about one third from the anterior edge of the upper margin; they are slightly inflated, rather elevated, and sculptured with small Wavy wrinkles and traces of small knobs, the wrinkles extend towards the front and also, though indistinctly, towards the posterior slope. Ligament rather long, narrow, yellowish brown. From the beaks two shallow grooves are running towards the posterior margin, which correspond with the green rays. Inside of the shell nacreous, nacre rosy. Hinge and teeth very thin, right valve with an elongate triangular tooth, with a slightly notched crest, lateral tooth much elongated, slightly furrowed lengthwise; left valve with a very indistinct tooth and two lateral ones; anterior muscular scars shallow, posterior ones and pallial scar scarcely visible. Length 41, breadth under the beaks 19, behind the ligament 22 mill. Diam. 18 mill.