NEW AND LITTLE KNOWN SPECIES OF SOUTH AMERICAN MUSSELS OF THE GENUS DIPLODON. By William B. Marshall (Proc. U. S. Nat. Museum, Vol. 53, pp. 381‒388, Pls. 50‒55, August, 1917). Two new species _Diplodon felipponei_ and _D. fortis_ are described and figured, together with six species described by Mr. C. T. Simpson in his Descriptive Catalogue of the Naiades and not previously figured. * * * * * NOTES ON THE SHELLS OF THE GENUS EPITONIUM AND ITS ALLIES OF THE PACIFIC COAST OF AMERICA. By William H. Dall (Proc. U. S. Nat. Museum, Vol. 53, pp. 471‒488, August, 1917). An interesting account of the various groups and subgenera is followed by descriptions of forty-two new species. The name Pictoscala is proposed for a section, type _Scalaria lineata_ Say. * * * * * STUDIES ON AUSTRALIAN MOLLUSCA. PT. XIII. By C. Hedley (Proc. Linn. Soc. New South Wales, 1916, vol. 41, pt. 4, pp. 680‒719, pls. 46‒52, issued April 4, 1917). The author’s notes under _Tridacna gigantea_ Perry are of such general interest that we quote them in part. “Under the name of _Chama gigas_ the father of Natural History seems to have embraced the whole of the modern genus _Tridacna_. For the name _gigas_, as restricted to a single species, the candidates are the shell subsequently named _squamosa_ by Lamarck and a huge species whose valves in the Ulrica Museum, together weighed 498 pounds. “After careful examination, Hanley decided that the furbelowed clam, such as Reeve has figured for _T. squamosa_, ought rightly to bear the name _gigas_. He based his verdict on the ground that the actual shell owned by Linné as representing _gigas_, is the Lamarckian _squamosa_, and that to this apply most of the literary references. Linnean contemporaries such as Born, Regenfuss and Chemnitz, while making casual references to the giant, all agree in figuring and describing _squamosa_ as the Linnean _gigas_. “Discriminating in 1819 between the species his predecessors had confused, Lamarck unlawfully used the name _gigas_ for the largest form, while for the Linnean _gigas_ he proposed _squamosa_. Attentive to the remarks of Hanley, Hidalgo in 1903, renamed the biggest species _T. lamarcki_. But in 1811, Perry had already used the name _Chama gigantea_ for ‘the largest shell at present known.’ As the young of the giant has not yet been traced to the adult, it is still possible that _squamosa_ is a juvenile deeper-water form of the large intertidal and abraded _gigantea_. “The heaviest known are a pair weighing 550 lbs., which Cuvier and Lamarck relate were presented by the Venetian Republic to Francis I. These still exist, their edges bound with brass, as holy-water basins in the cathedral of St. Sulpice, in Paris.