289 



Distribution : — Lzmulicardia retusa has been recorded from the Gulf of Suez, various 

 localities in the Indian Océan, the Gulf of Siam, round PhiHppines and the Torres Straits. 



In the "Siboga" collection the species is represented by a number of young shells 

 collected at the Anchorage off Pulu Kawassang, Pàternoster Islands (St. 40) and the Anchorage 

 off North Ubian (St. 99). 



Family Tancrediidae. 

 Genus Hemidonax Môrch. 



1870. Hemidonax Morch, Malakozool, Blàtt., XVII, p. 121. 



1887. Hemidonax Fischer, P., Man. ConchylioL, p. iioi. 



1900. Hemidonax Dali, Trans. Wagner Free Inst. Sci. Philadelphia, III, p. 963. 



The exact position of the genus Hiniidonax-X.y^Q, Hemidonax donaciformis (Bruguière), 

 is a matter for discussion. Species of the genus were described and included in the genus Cardium 

 Linn., but as Pelseneer ^) pointed out the structure of the foot of Hemidonax donaciformis is 

 entirely différent from that of the genus Cardium, and this alone would justify its séparation 

 as a distinct family. Fischer included it in the family Tancrediidae which he placed between the 

 familles Unicardiidae and Donacidae ; Dall has included it in the Donacidae. The genus in 

 form, structure and ornamentation of the shells resembles Donax, but the palliai line is entire 

 or unsinuated, and there are two latéral teeth on each side in the right valve. 



I. Hemidonax donaciformis (Bruguière). 



1782, Cardium médium Chemnitz (ex parte, non Linnaeus), Conch.-Cab., VI, p. 171, pi. XVI, 

 fig. 165. 



1788. Cardium médium Schrôter (ex parte, non Linnaeus), Conch.-Cab. Namen Reg., p. 19. 



1789. Cardium donaciforme, Bruguière, Encyclopéd. Méthod., I, p. 214. 



1790. Cardium médium var. B., .Gmelin (non Linnaeus) Syst. Nat., (éd. XIII), p. 3247. 

 1797. Bruguière, Encyclopéd. Méthod., pi. CCXCVI, fig. 2. 



1799. Cardium donaceum, Spengler, Skr. Nat. Hist. Selsk., V, p. 37. 



1802. Cardium donaciforme Bosc, Hist. Nat. Coq., III. p. 99. 



1817. Cardium donaciforme Dillwyn, Descr. Cat., I, p. 114. 



1818. Cardium cardioides Laniarck, Anim. sans Vertèb., V, p. 550. 



1824. Cardium cardioides Dubois, Epitome, p. 62. 



1825. Cardium Donaciforme Wood, Ind. Test., p. 27, pi. V, fig. 38. 



1834. Cardium Cardioides, Quoy & Gaimard, Voy. "Astrolabe", III, p. 495, pi. LXXXI, 



figs. 17—19. 

 1841. Cardium donaciforme Sowerby, Conch. Illustr., Cat., p. 6, figs. 26, 27. 



1843. Cardium Donaciforine Hanley, ■ Rev. Biv. Shells, p. 144. 



1844. Cardium. Australiense and D. donaciforme, Reeve, Conch. Icon., II, Cardium, pi. V 



figs. 24, 25. 



1845. Cardium Australiense Reeve, Proc. Zool. Soc. London (vol. for 1844), p. 168. 

 1845. Cardium Donaciforme Catlow & Reeve, Conch, NomencL, p. 42. 



1853. Fragum [Hemicardium] donaciforme Morch, Cat. Yoldi, p. 35. 



1856. Cardium Donaciforme Hanley, in Wood Ind. Test., p. 35, pi. V, fig. 38. 



i) Pelseneer, p. — "Siboga" Lamellibranches (Anat.), p. 38 (191 1). 



SIBOGA-EXPEDITIE lAWC. 37 



