14 THE NAUTILUS. 



This shell is not closely allied to any shell with which I am 

 acquainted. On the one hand it resembles some of the Pleurobemas 

 of the group typified by P. fassinans, Lea, and on the other hand it 

 bears some resemblance to a young and thin Q. aurea, Lea. In the 

 concentric coloring of the lines of growth, it reminds one of Q. 

 asperata, Lea. Its deep and compressed beak cavities place it in 

 the genus Quadrula, while its resemblances to the latter two species 

 is too slight to cause any error in their direction. Four specimens 

 were found in the Tallapoosa River, Ala., by Mr. A. A. Hinkley, 

 who has kindly allowed me to retain the specimen figured. 



Quadrula rubidida n. sp. Plate I, figs. 3. 4. 



Shell small, heavy, somewhat triangular; base emarginate, dor- 

 sum arched, posterior angle biangulate; ligament elevated, light red. 

 Beaks not very high, umbones inflated, sides flattened, epidermis 

 brown, rough, obsoletely rayed, and showing traces of a greenish 

 tint. 



Cardinals stout, short, rough, inclined to be double in both valves; 

 laterals rather short, heavy, rough, and slightly curved ; cavity of 

 shell very irregular, excavated from beak to posterior margin; beak 

 cavity deep and compressed, nacre white, sometimes pinkish, not 

 very iridescent. Long. 36, alt. 32, diam. 22 mm. 



The shell is close to Q. rubida, Lea, and some forms resemble 

 some of the depauperated specimens of Q. trigona, Lea. From 

 either of these species it may be differentiated by its small size, and 

 by the biangulated posterior angle. Some 30 or 40 specimens from 

 the Mulberry River; 20 or 30 from the Black Warrior, and a single 

 specimen from the North River, Alabama, show a remarkable con- 

 stancy in size and other characters. Examples may be seen in the 

 cabinets of most of the collectors of Unionidae in America, contributed 

 by Mr. A. A. Hinkley, of Dubois, Illinois. 



TWO TJNDESCRIBED CALIFORNIA!* SHELLS. 



BY WILLIAM HEALEY DALL. 



Murex (Phyllonotus) santarosana n. sp. 



Shell small for the subgenus, with about six whorls, each bearing 

 from five to seven strong, low, reflexed varices, with a prominent, 



