118 THE NAUTILUS. 



Examples are in the collections of the Academy of Natural 

 Science, Philadelphia ; The National Museum ; The Chicago 

 Academy of Science, Mr. Bryant "Walker, and the writer. 



NOTES ON SOME AUSTRALIAN UNIONID.E. 



BY L. S. FRIERSON. 



A series of shells covering nearly the whole range of species 

 credited to Australia having been received from the well-known 

 conchologist, Mr. Wm. T. Bednall of Adelaide, reveals several inter- 

 esting points, which may constitute as many " addenda and corri- 

 genda " to Mr. C. T. Simpson's " Synopsis of the Naiades." 



Page 891. TJnio bednalli Tate was described in 1882, Proceed- 

 ings Royal Society of South Australia, page 56. The shell, as 

 evidenced by notes, and a fine series of specimens from Mr. Bednall, 

 is not a form of Diplodon australis (Lam.) Hanley, but is much 

 nearer to D. wilsonii Lea (= stuarti Adams and Angas). A speci- 

 men of bednalli is over 3^ inches long by If high, whereas a speci- 

 men of D. australis var. legrandi (an elongated variety) is 3 inches 

 long and 2 inches high). D. bednalli Tate therefore should be 

 removed as a synonym of australis, and restored to specific rank, 

 from whence, should it ever be degraded, it must fall under D. wil- 

 sonii Lea, as a variety. 



A series of shells labeled U. angasii Lea revealed the follow- 

 ing facts : U. angasii, credited to MSS. of Lea, was described by 

 Sowerby in Conchologia Iconica, and placed by Mr. Simpson as a 

 synonym of D. shuttleworthii Lea. A casual observation of the lot 

 seemed to indicate two species. A critical study of both the actual 

 specimens with the original descriptions of both species confirmed 

 this impression. Diplodon shuttleworthii Lea (besides being appar- 

 ently larger) has a deeply and coarsely sulcated disc, and is covered 

 with a heavy, thick, scaly epidermis resembling that of D. cucumoides. 



On the other hand the D. angasii Sowerby is apparently a smaller 

 species, is much thinner, with a smooth surface and covered with a 

 thin epidermis, with nothing more than fine sulcations, scarcely 

 noticeable. But as a final clincher, a young specimen of D. angasii 

 (having beaks so perfect as to show the glochidial shell) show* a 



