784 PROCEEDINGS OF THE NATIONAL MUSEUM vol.xxiii. 



1889. Dall, Proceedings, U. S. National Museum, XII, No. 773. ||| 



1889. Dall, Bulletin, U. S. National Museum, No. 37. "1 



1889. Heilprin, The Bermuda Islands. 



1890. Stearns, Proceedings, U. S. National Museum, XIII, No. 813. 



1891. Pilsbry, List of Mollusca collected by Frederick Stearns in Japan. 

 1893. BrsH, Bulletin, ^Museum of Comparative Zoology, XXIII, No. 6. 



1895. Dall, The Nautilus, IX, No. 7. 



1896. LocARD, Annales de I'universite de Lyon, Campagne du Caudan. 

 1896. Dall, The Nautilus, X, No. 5, September. 



1898. Verrill and BrsH, Proceedings, U. S. National Museum, XX, No. 1139. 

 1898. Locard, Expeditions scientifiques du Travailleur et du Talisman, II. 

 1898. BucQUOY, Dautzenberg et Dollfus, Mollusques Marins du Roussillon, II. 



1898. PossELT, Conspectus Fauna Gronlandia?. 



1899. Dall, Transactions Wagner Free Institute of Science, III, part 5. 

 1899. Grzybowski, Neuen Jahrbuch fiir Mineralogie, Beilageband, XII. 

 1901. Dall and Simpson, Report on the MoUusks of Porto Rico. 



Family THYASIRID^. 



{Cryptodontidiv of authors.) 

 Genus THYASIRA Leach. 



This is Thyasira Leach (in Lamarck, 1818); Thyatira Jg.^yqjs, 1839, 

 not Hiibner, 1816; Bequania Leach (in Brown, 1827); Axmus J. Sow- 

 erby, 1821, not^4*'/;;« Kirby, 1817; Cryptodoii Turton, 1822; Clausina 

 Jeffreys, 1817, not Brown, 1827; Ptychma Philippi, 1836; Cryptodon^ 

 (Turton) Dall, 1889, not of Conrad, 1837; ScliizothmrMS Locard, 1898, 

 not of Conrad, 1853; Philis Fischer, 1861; Conchocele G^ihh^ 1866; Meg- 

 axinus Brugnone, 1881; Axinidus Verrill and Bush, 1898; Axinodoii 

 Verrill and Bush, 1898; and Luchia (sp.) of various earlier authors. 



The genus is divisible as follows: 

 Section Thyasira s. s. 



Valves with edentulous hinge, the anterior dorsal area more or less 

 impressed, the posterior more or less distinctly radially salcate or 

 plicate. 



Type, TelUna flexuom, Montagu, 1803, + Venus sinnosa Donovan, 

 1801, not of Pennant, 1777; + Lucina sinuata Lamarck, 1818; + Pty- 

 ch'ina hiplicata Philippi, 1836; + Cryptodon hisinuatus S. Wood, 18-10; 

 + Axin us sinuatus Philippi, 1845. North Atlantic south to the Azores 

 and Mediterranean. 



PhiUs Fischer, intergrades with the other species. Megaxhius 

 Brugnone, differs only by more solid shell and larger nymphs. 

 Section Axinidus \ QvriW and Bush, 1898. 



Shell minute, ovate or oblong, with the dorsal areas obsolete. 



These forms intergrade imperceptibly with those of the previous 

 section; Axinodo7iY cvviW and Bush, appears to differ b}'- no substantial 

 characters. 



' " Crypiodo)! " moseleyi and luzoniciix Smith, do not belong in this family and their 

 place is uncertain. 



