Unionidse from East Asia. 497 



in front, distinctly triangulate behind. Posterior ridge rather 

 high, rounded. Basal margin almost straight. Beaks not 

 prominent, situated at ] 2 6 q of the total length, greatly eroded ; 

 their sculpture covers the greatest part of the disk and con- 

 sists of concentrical, wavy wrinkles standing very close. 

 Epidermis of a dull blackish grey. Hinge consisting of two 

 cardinals and two laterals in the left, one cardinal and one 

 lateral in the right valve. Cardinals rather solid, stumpy, 

 that of the right valve accompanied in front by a low lamellar 

 auxiliary tooth. Laterals nearly straight, high. Interval 

 short, rather smooth. Anterior cicatrices distinct, deep ; 

 posterior distinct and very faint. Dorsal cicatrices united to 

 a narrow groove situated at the inner side of the interval. 

 Beak-cavities rather deep. Nacre silvery. 



Length 53, height 26, diam. 18 mm. 



Hob. Hainan. Collected by Mr. B. Schmacker. 



Four specimens in the Senckenberg Museum. 



2. Nodularia continentalis, sp. n. 



Shell elongate-elliptical, solid, inflated, somewhat truncated 

 in front and slightly arcuate behind. Posterior ridge mode- 

 rate, rounded. Basal margin slightly sinuate at its posterior 

 part. Beaks not prominent, eroded, situated at y 2 ^ of the 

 total length ; their sculpture is not to be seen when adult, in 

 young shells it consists of few concentrical, slightly looped 

 ridges, the posterior loops running upwards across the poste- 

 rior slope. Epidermis of a rather dull black. Hinge con- 

 sisting of two cardinals and two laterals in the left, one 

 cardinal and one lateral in the right valve. Cardinals solid, 

 stumpy, jagged on the surface, a narrow lamellar auxiliary 

 tooth standing in front of the one of the right valve. Laterals 

 long, high and curved. Interval short, broad, covered with 

 small denticular structures. Anterior cicatrices distinct, deep ; 

 posterior distinct, faint. Dorsal cicatrices uuited to a narrow 

 short groove situated at the inner side of the interval. Beak- 

 cavities deep. Nacre silvery, brilliant. 



Length 62, height 36, diam. 25 mm. 



Bab. Hunan, Middle China. Collected by Dr. O. v. 

 Moellendorff. 



Two specimens in the Senckenberg Museum. 



Very near to Nod. japanensis, Lea, of Japan, the first form 

 of this group recorded from the continent. 



3. Nodularia undulata, sp. n. 

 Shell rhomboid-elliptical, rather thin and moderately 



