UNIO LANDANENSIS. 113 



NOTE IX. 

 A NEW SPECIES OF UNIO. 



DESCRIBED BY 



M. M. SCHEPMAN. 



Unio landanensis , n. sp. 



(Plate 8, fig. 3). 



Shell oblong, attenuated towards the anterior part, in- 

 aequilateral , rather inflated, very thin, rather smooth but 

 covered with a thin closely wrinkled epidermis, greeuish- 

 olive , with two indistinct green rays on the posterior slope. 

 Upper- or hinge-margin nearly straight, lower margin ir- 

 regularly 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 gra- 

 dually sloping to a wedgelike point. Beaks slightly in- 

 curved , 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 length- 

 Notes from tlie Leyden jVLuseum , Vol. X^III. 



